#ifdef __LONG_DOUBLE_128__

/* Avoid using inline namespace not supported by GCC 4.2 */

#undef __LONG_DOUBLE_128__

#include_next <bits/c++config.h>

#define __LONG_DOUBLE_128__ 1

#else

#include_next <bits/c++config.h>

#endif

/* GCC 4.2 parser does not support __int128 */

#undef _GLIBCXX_USE_INT128

// Algorithm implementation -*- C++ -*-

// Copyright (C) 2001-2014 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library is free

// software; you can redistribute it and/or modify it under the

// terms of the GNU General Public License as published by the

// Free Software Foundation; either version 3, or (at your option)

// any later version.

// This library is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// <http://www.gnu.org/licenses/>.

/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/** @file bits/stl_algo.h

 *  This is an internal header file, included by other library headers.

 *  Do not attempt to use it directly. @headername{algorithm}

 */

#ifndef _STL_ALGO_H

#define _STL_ALGO_H 1

#include <cstdlib>             // for rand

#include <bits/algorithmfwd.h>

#include <bits/stl_heap.h>

#include <bits/stl_tempbuf.h>  // for _Temporary_buffer

#include <bits/predefined_ops.h>

#if __cplusplus >= 201103L

#include <random>     // for std::uniform_int_distribution

#endif

// See concept_check.h for the __glibcxx_*_requires macros.

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /// Swaps the median value of *__a, *__b and *__c under __comp to *__result

  template<typename _Iterator, typename _Compare>

    void

    __move_median_to_first(_Iterator __result,_Iterator __a, _Iterator __b,

			   _Iterator __c, _Compare __comp)

    {

      if (__comp(__a, __b))

	{

	  if (__comp(__b, __c))

	    std::iter_swap(__result, __b);

	  else if (__comp(__a, __c))

	    std::iter_swap(__result, __c);

	  else

	    std::iter_swap(__result, __a);

	}

      else if (__comp(__a, __c))

	std::iter_swap(__result, __a);

      else if (__comp(__b, __c))

	std::iter_swap(__result, __c);

      else

	std::iter_swap(__result, __b);

    }

  /// This is an overload used by find algos for the Input Iterator case.

  template<typename _InputIterator, typename _Predicate>

    inline _InputIterator

    __find_if(_InputIterator __first, _InputIterator __last,

	      _Predicate __pred, input_iterator_tag)

    {

      while (__first != __last && !__pred(__first))

	++__first;

      return __first;

    }

  /// This is an overload used by find algos for the RAI case.

  template<typename _RandomAccessIterator, typename _Predicate>

    _RandomAccessIterator

    __find_if(_RandomAccessIterator __first, _RandomAccessIterator __last,

	      _Predicate __pred, random_access_iterator_tag)

    {

      typename iterator_traits<_RandomAccessIterator>::difference_type

	__trip_count = (__last - __first) >> 2;

      for (; __trip_count > 0; --__trip_count)

	{

	  if (__pred(__first))

	    return __first;

	  ++__first;

	  if (__pred(__first))

	    return __first;

	  ++__first;

	  if (__pred(__first))

	    return __first;

	  ++__first;

	  if (__pred(__first))

	    return __first;

	  ++__first;

	}

      switch (__last - __first)

	{

	case 3:

	  if (__pred(__first))

	    return __first;

	  ++__first;

	case 2:

	  if (__pred(__first))

	    return __first;

	  ++__first;

	case 1:

	  if (__pred(__first))

	    return __first;

	  ++__first;

	case 0:

	default:

	  return __last;

	}

    }

  template<typename _Iterator, typename _Predicate>

    inline _Iterator

    __find_if(_Iterator __first, _Iterator __last, _Predicate __pred)

    {

      return __find_if(__first, __last, __pred,

		       std::__iterator_category(__first));

    }

  /// Provided for stable_partition to use.

  template<typename _InputIterator, typename _Predicate>

    inline _InputIterator

    __find_if_not(_InputIterator __first, _InputIterator __last,

		  _Predicate __pred)

    {

      return std::__find_if(__first, __last,

			    __gnu_cxx::__ops::__negate(__pred),

			    std::__iterator_category(__first));

    }

  /// Like find_if_not(), but uses and updates a count of the

  /// remaining range length instead of comparing against an end

  /// iterator.

  template<typename _InputIterator, typename _Predicate, typename _Distance>

    _InputIterator

    __find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)

    {

      for (; __len; --__len, ++__first)

	if (!__pred(__first))

	  break;

      return __first;

    }

  // set_difference

  // set_intersection

  // set_symmetric_difference

  // set_union

  // for_each

  // find

  // find_if

  // find_first_of

  // adjacent_find

  // count

  // count_if

  // search

  template<typename _ForwardIterator1, typename _ForwardIterator2,

	   typename _BinaryPredicate>

    _ForwardIterator1

    __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,

	     _ForwardIterator2 __first2, _ForwardIterator2 __last2,

	     _BinaryPredicate  __predicate)

    {

      // Test for empty ranges

      if (__first1 == __last1 || __first2 == __last2)

	return __first1;

      // Test for a pattern of length 1.

      _ForwardIterator2 __p1(__first2);

      if (++__p1 == __last2)

	return std::__find_if(__first1, __last1,

		__gnu_cxx::__ops::__iter_comp_iter(__predicate, __first2));

      // General case.

      _ForwardIterator2 __p;

      _ForwardIterator1 __current = __first1;

      for (;;)

	{

	  __first1 =

	    std::__find_if(__first1, __last1,

		__gnu_cxx::__ops::__iter_comp_iter(__predicate, __first2));

	  if (__first1 == __last1)

	    return __last1;

	  __p = __p1;

	  __current = __first1;

	  if (++__current == __last1)

	    return __last1;

	  while (__predicate(__current, __p))

	    {

	      if (++__p == __last2)

		return __first1;

	      if (++__current == __last1)

		return __last1;

	    }

	  ++__first1;

	}

      return __first1;

    }

  // search_n

  /**

   *  This is an helper function for search_n overloaded for forward iterators.

  */

  template<typename _ForwardIterator, typename _Integer,

	   typename _UnaryPredicate>

    _ForwardIterator

    __search_n_aux(_ForwardIterator __first, _ForwardIterator __last,

		   _Integer __count, _UnaryPredicate __unary_pred,

		   std::forward_iterator_tag)

    {

      __first = std::__find_if(__first, __last, __unary_pred);

      while (__first != __last)

	{

	  typename iterator_traits<_ForwardIterator>::difference_type

	    __n = __count;

	  _ForwardIterator __i = __first;

	  ++__i;

	  while (__i != __last && __n != 1 && __unary_pred(__i))

	    {

	      ++__i;

	      --__n;

	    }

	  if (__n == 1)

	    return __first;

	  if (__i == __last)

	    return __last;

	  __first = std::__find_if(++__i, __last, __unary_pred);

	}

      return __last;

    }

  /**

   *  This is an helper function for search_n overloaded for random access

   *  iterators.

  */

  template<typename _RandomAccessIter, typename _Integer,

	   typename _UnaryPredicate>

    _RandomAccessIter

    __search_n_aux(_RandomAccessIter __first, _RandomAccessIter __last,

		   _Integer __count, _UnaryPredicate __unary_pred,

		   std::random_access_iterator_tag)

    {

      typedef typename std::iterator_traits<_RandomAccessIter>::difference_type

	_DistanceType;

      _DistanceType __tailSize = __last - __first;

      _DistanceType __remainder = __count;

      while (__remainder <= __tailSize) // the main loop...

	{

	  __first += __remainder;

	  __tailSize -= __remainder;

	  // __first here is always pointing to one past the last element of

	  // next possible match.

	  _RandomAccessIter __backTrack = __first; 

	  while (__unary_pred(--__backTrack))

	    {

	      if (--__remainder == 0)

	        return (__first - __count); // Success

	    }

	  __remainder = __count + 1 - (__first - __backTrack);

	}

      return __last; // Failure

    }

  template<typename _ForwardIterator, typename _Integer,

           typename _UnaryPredicate>

    _ForwardIterator

    __search_n(_ForwardIterator __first, _ForwardIterator __last,

	       _Integer __count,

	       _UnaryPredicate __unary_pred)

    {

      if (__count <= 0)

	return __first;

      if (__count == 1)

	return std::__find_if(__first, __last, __unary_pred);

      return std::__search_n_aux(__first, __last, __count, __unary_pred,

				 std::__iterator_category(__first));

    }

  // find_end for forward iterators.

  template<typename _ForwardIterator1, typename _ForwardIterator2,

	   typename _BinaryPredicate>

    _ForwardIterator1

    __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,

	       _ForwardIterator2 __first2, _ForwardIterator2 __last2,

	       forward_iterator_tag, forward_iterator_tag,

	       _BinaryPredicate __comp)

    {

      if (__first2 == __last2)

	return __last1;

      _ForwardIterator1 __result = __last1;

      while (1)

	{

	  _ForwardIterator1 __new_result

	    = std::__search(__first1, __last1, __first2, __last2, __comp);

	  if (__new_result == __last1)

	    return __result;

	  else

	    {

	      __result = __new_result;

	      __first1 = __new_result;

	      ++__first1;

	    }

	}

    }

  // find_end for bidirectional iterators (much faster).

  template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,

	   typename _BinaryPredicate>

    _BidirectionalIterator1

    __find_end(_BidirectionalIterator1 __first1,

	       _BidirectionalIterator1 __last1,

	       _BidirectionalIterator2 __first2,

	       _BidirectionalIterator2 __last2,

	       bidirectional_iterator_tag, bidirectional_iterator_tag,

	       _BinaryPredicate __comp)

    {

      // concept requirements

      __glibcxx_function_requires(_BidirectionalIteratorConcept<

				  _BidirectionalIterator1>)

      __glibcxx_function_requires(_BidirectionalIteratorConcept<

				  _BidirectionalIterator2>)

      typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;

      typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;

      _RevIterator1 __rlast1(__first1);

      _RevIterator2 __rlast2(__first2);

      _RevIterator1 __rresult = std::__search(_RevIterator1(__last1), __rlast1,

					      _RevIterator2(__last2), __rlast2,

					      __comp);

      if (__rresult == __rlast1)

	return __last1;

      else

	{

	  _BidirectionalIterator1 __result = __rresult.base();

	  std::advance(__result, -std::distance(__first2, __last2));

	  return __result;

	}

    }

  /**

   *  @brief  Find last matching subsequence in a sequence.

   *  @ingroup non_mutating_algorithms

   *  @param  __first1  Start of range to search.

   *  @param  __last1   End of range to search.

   *  @param  __first2  Start of sequence to match.

   *  @param  __last2   End of sequence to match.

   *  @return   The last iterator @c i in the range

   *  @p [__first1,__last1-(__last2-__first2)) such that @c *(i+N) ==

   *  @p *(__first2+N) for each @c N in the range @p

   *  [0,__last2-__first2), or @p __last1 if no such iterator exists.

   *

   *  Searches the range @p [__first1,__last1) for a sub-sequence that

   *  compares equal value-by-value with the sequence given by @p

   *  [__first2,__last2) and returns an iterator to the __first

   *  element of the sub-sequence, or @p __last1 if the sub-sequence

   *  is not found.  The sub-sequence will be the last such

   *  subsequence contained in [__first1,__last1).

   *

   *  Because the sub-sequence must lie completely within the range @p

   *  [__first1,__last1) it must start at a position less than @p

   *  __last1-(__last2-__first2) where @p __last2-__first2 is the

   *  length of the sub-sequence.  This means that the returned

   *  iterator @c i will be in the range @p

   *  [__first1,__last1-(__last2-__first2))

  */

  template<typename _ForwardIterator1, typename _ForwardIterator2>

    inline _ForwardIterator1

    find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,

	     _ForwardIterator2 __first2, _ForwardIterator2 __last2)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)

      __glibcxx_function_requires(_EqualOpConcept<

	    typename iterator_traits<_ForwardIterator1>::value_type,

	    typename iterator_traits<_ForwardIterator2>::value_type>)

      __glibcxx_requires_valid_range(__first1, __last1);

      __glibcxx_requires_valid_range(__first2, __last2);

      return std::__find_end(__first1, __last1, __first2, __last2,

			     std::__iterator_category(__first1),

			     std::__iterator_category(__first2),

			     __gnu_cxx::__ops::__iter_equal_to_iter());

    }

  /**

   *  @brief  Find last matching subsequence in a sequence using a predicate.

   *  @ingroup non_mutating_algorithms

   *  @param  __first1  Start of range to search.

   *  @param  __last1   End of range to search.

   *  @param  __first2  Start of sequence to match.

   *  @param  __last2   End of sequence to match.

   *  @param  __comp    The predicate to use.

   *  @return The last iterator @c i in the range @p

   *  [__first1,__last1-(__last2-__first2)) such that @c

   *  predicate(*(i+N), @p (__first2+N)) is true for each @c N in the

   *  range @p [0,__last2-__first2), or @p __last1 if no such iterator

   *  exists.

   *

   *  Searches the range @p [__first1,__last1) for a sub-sequence that

   *  compares equal value-by-value with the sequence given by @p

   *  [__first2,__last2) using comp as a predicate and returns an

   *  iterator to the first element of the sub-sequence, or @p __last1

   *  if the sub-sequence is not found.  The sub-sequence will be the

   *  last such subsequence contained in [__first,__last1).

   *

   *  Because the sub-sequence must lie completely within the range @p

   *  [__first1,__last1) it must start at a position less than @p

   *  __last1-(__last2-__first2) where @p __last2-__first2 is the

   *  length of the sub-sequence.  This means that the returned

   *  iterator @c i will be in the range @p

   *  [__first1,__last1-(__last2-__first2))

  */

  template<typename _ForwardIterator1, typename _ForwardIterator2,

	   typename _BinaryPredicate>

    inline _ForwardIterator1

    find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,

	     _ForwardIterator2 __first2, _ForwardIterator2 __last2,

	     _BinaryPredicate __comp)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)

      __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,

	    typename iterator_traits<_ForwardIterator1>::value_type,

	    typename iterator_traits<_ForwardIterator2>::value_type>)

      __glibcxx_requires_valid_range(__first1, __last1);

      __glibcxx_requires_valid_range(__first2, __last2);

      return std::__find_end(__first1, __last1, __first2, __last2,

			     std::__iterator_category(__first1),

			     std::__iterator_category(__first2),

			     __gnu_cxx::__ops::__iter_comp_iter(__comp));

    }

#if __cplusplus >= 201103L

  /**

   *  @brief  Checks that a predicate is true for all the elements

   *          of a sequence.

   *  @ingroup non_mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __pred    A predicate.

   *  @return  True if the check is true, false otherwise.

   *

   *  Returns true if @p __pred is true for each element in the range

   *  @p [__first,__last), and false otherwise.

  */

  template<typename _InputIterator, typename _Predicate>

    inline bool

    all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)

    { return __last == std::find_if_not(__first, __last, __pred); }

  /**

   *  @brief  Checks that a predicate is false for all the elements

   *          of a sequence.

   *  @ingroup non_mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __pred    A predicate.

   *  @return  True if the check is true, false otherwise.

   *

   *  Returns true if @p __pred is false for each element in the range

   *  @p [__first,__last), and false otherwise.

  */

  template<typename _InputIterator, typename _Predicate>

    inline bool

    none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)

    { return __last == _GLIBCXX_STD_A::find_if(__first, __last, __pred); }

  /**

   *  @brief  Checks that a predicate is false for at least an element

   *          of a sequence.

   *  @ingroup non_mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __pred    A predicate.

   *  @return  True if the check is true, false otherwise.

   *

   *  Returns true if an element exists in the range @p

   *  [__first,__last) such that @p __pred is true, and false

   *  otherwise.

  */

  template<typename _InputIterator, typename _Predicate>

    inline bool

    any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)

    { return !std::none_of(__first, __last, __pred); }

  /**

   *  @brief  Find the first element in a sequence for which a

   *          predicate is false.

   *  @ingroup non_mutating_algorithms

   *  @param  __first  An input iterator.

   *  @param  __last   An input iterator.

   *  @param  __pred   A predicate.

   *  @return   The first iterator @c i in the range @p [__first,__last)

   *  such that @p __pred(*i) is false, or @p __last if no such iterator exists.

  */

  template<typename _InputIterator, typename _Predicate>

    inline _InputIterator

    find_if_not(_InputIterator __first, _InputIterator __last,

		_Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	      typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__find_if_not(__first, __last,

				__gnu_cxx::__ops::__pred_iter(__pred));

    }

  /**

   *  @brief  Checks whether the sequence is partitioned.

   *  @ingroup mutating_algorithms

   *  @param  __first  An input iterator.

   *  @param  __last   An input iterator.

   *  @param  __pred   A predicate.

   *  @return  True if the range @p [__first,__last) is partioned by @p __pred,

   *  i.e. if all elements that satisfy @p __pred appear before those that

   *  do not.

  */

  template<typename _InputIterator, typename _Predicate>

    inline bool

    is_partitioned(_InputIterator __first, _InputIterator __last,

		   _Predicate __pred)

    {

      __first = std::find_if_not(__first, __last, __pred);

      return std::none_of(__first, __last, __pred);

    }

  /**

   *  @brief  Find the partition point of a partitioned range.

   *  @ingroup mutating_algorithms

   *  @param  __first   An iterator.

   *  @param  __last    Another iterator.

   *  @param  __pred    A predicate.

   *  @return  An iterator @p mid such that @p all_of(__first, mid, __pred)

   *           and @p none_of(mid, __last, __pred) are both true.

  */

  template<typename _ForwardIterator, typename _Predicate>

    _ForwardIterator

    partition_point(_ForwardIterator __first, _ForwardIterator __last,

		    _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	      typename iterator_traits<_ForwardIterator>::value_type>)

      // A specific debug-mode test will be necessary...

      __glibcxx_requires_valid_range(__first, __last);

      typedef typename iterator_traits<_ForwardIterator>::difference_type

	_DistanceType;

      _DistanceType __len = std::distance(__first, __last);

      _DistanceType __half;

      _ForwardIterator __middle;

      while (__len > 0)

	{

	  __half = __len >> 1;

	  __middle = __first;

	  std::advance(__middle, __half);

	  if (__pred(*__middle))

	    {

	      __first = __middle;

	      ++__first;

	      __len = __len - __half - 1;

	    }

	  else

	    __len = __half;

	}

      return __first;

    }

#endif

  template<typename _InputIterator, typename _OutputIterator,

	   typename _Predicate>

    _OutputIterator

    __remove_copy_if(_InputIterator __first, _InputIterator __last,

		     _OutputIterator __result, _Predicate __pred)

    {

      for (; __first != __last; ++__first)

	if (!__pred(__first))

	  {

	    *__result = *__first;

	    ++__result;

	  }

      return __result;

    }

  /**

   *  @brief Copy a sequence, removing elements of a given value.

   *  @ingroup mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __result  An output iterator.

   *  @param  __value   The value to be removed.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  Copies each element in the range @p [__first,__last) not equal

   *  to @p __value to the range beginning at @p __result.

   *  remove_copy() is stable, so the relative order of elements that

   *  are copied is unchanged.

  */

  template<typename _InputIterator, typename _OutputIterator, typename _Tp>

    inline _OutputIterator

    remove_copy(_InputIterator __first, _InputIterator __last,

		_OutputIterator __result, const _Tp& __value)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_function_requires(_EqualOpConcept<

	    typename iterator_traits<_InputIterator>::value_type, _Tp>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__remove_copy_if(__first, __last, __result,

	__gnu_cxx::__ops::__iter_equals_val(__value));

    }

  /**

   *  @brief Copy a sequence, removing elements for which a predicate is true.

   *  @ingroup mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __result  An output iterator.

   *  @param  __pred    A predicate.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  Copies each element in the range @p [__first,__last) for which

   *  @p __pred returns false to the range beginning at @p __result.

   *

   *  remove_copy_if() is stable, so the relative order of elements that are

   *  copied is unchanged.

  */

  template<typename _InputIterator, typename _OutputIterator,

	   typename _Predicate>

    inline _OutputIterator

    remove_copy_if(_InputIterator __first, _InputIterator __last,

		   _OutputIterator __result, _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__remove_copy_if(__first, __last, __result,

				   __gnu_cxx::__ops::__pred_iter(__pred));

    }

#if __cplusplus >= 201103L

  /**

   *  @brief Copy the elements of a sequence for which a predicate is true.

   *  @ingroup mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __result  An output iterator.

   *  @param  __pred    A predicate.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  Copies each element in the range @p [__first,__last) for which

   *  @p __pred returns true to the range beginning at @p __result.

   *

   *  copy_if() is stable, so the relative order of elements that are

   *  copied is unchanged.

  */

  template<typename _InputIterator, typename _OutputIterator,

	   typename _Predicate>

    _OutputIterator

    copy_if(_InputIterator __first, _InputIterator __last,

	    _OutputIterator __result, _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      for (; __first != __last; ++__first)

	if (__pred(*__first))

	  {

	    *__result = *__first;

	    ++__result;

	  }

      return __result;

    }

  template<typename _InputIterator, typename _Size, typename _OutputIterator>

    _OutputIterator

    __copy_n(_InputIterator __first, _Size __n,

	     _OutputIterator __result, input_iterator_tag)

    {

      if (__n > 0)

	{

	  while (true)

	    {

	      *__result = *__first;

	      ++__result;

	      if (--__n > 0)

		++__first;

	      else

		break;

	    }

	}

      return __result;

    }

  template<typename _RandomAccessIterator, typename _Size,

	   typename _OutputIterator>

    inline _OutputIterator

    __copy_n(_RandomAccessIterator __first, _Size __n,

	     _OutputIterator __result, random_access_iterator_tag)

    { return std::copy(__first, __first + __n, __result); }

  /**

   *  @brief Copies the range [first,first+n) into [result,result+n).

   *  @ingroup mutating_algorithms

   *  @param  __first  An input iterator.

   *  @param  __n      The number of elements to copy.

   *  @param  __result An output iterator.

   *  @return  result+n.

   *

   *  This inline function will boil down to a call to @c memmove whenever

   *  possible.  Failing that, if random access iterators are passed, then the

   *  loop count will be known (and therefore a candidate for compiler

   *  optimizations such as unrolling).

  */

  template<typename _InputIterator, typename _Size, typename _OutputIterator>

    inline _OutputIterator

    copy_n(_InputIterator __first, _Size __n, _OutputIterator __result)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

	    typename iterator_traits<_InputIterator>::value_type>)

      return std::__copy_n(__first, __n, __result,

			   std::__iterator_category(__first));

    }

  /**

   *  @brief Copy the elements of a sequence to separate output sequences

   *         depending on the truth value of a predicate.

   *  @ingroup mutating_algorithms

   *  @param  __first   An input iterator.

   *  @param  __last    An input iterator.

   *  @param  __out_true   An output iterator.

   *  @param  __out_false  An output iterator.

   *  @param  __pred    A predicate.

   *  @return   A pair designating the ends of the resulting sequences.

   *

   *  Copies each element in the range @p [__first,__last) for which

   *  @p __pred returns true to the range beginning at @p out_true

   *  and each element for which @p __pred returns false to @p __out_false.

  */

  template<typename _InputIterator, typename _OutputIterator1,

	   typename _OutputIterator2, typename _Predicate>

    pair<_OutputIterator1, _OutputIterator2>

    partition_copy(_InputIterator __first, _InputIterator __last,

		   _OutputIterator1 __out_true, _OutputIterator2 __out_false,

		   _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator1,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator2,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      for (; __first != __last; ++__first)

	if (__pred(*__first))

	  {

	    *__out_true = *__first;

	    ++__out_true;

	  }

	else

	  {

	    *__out_false = *__first;

	    ++__out_false;

	  }

      return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);

    }

#endif

  template<typename _ForwardIterator, typename _Predicate>

    _ForwardIterator

    __remove_if(_ForwardIterator __first, _ForwardIterator __last,

		_Predicate __pred)

    {

      __first = std::__find_if(__first, __last, __pred);

      if (__first == __last)

        return __first;

      _ForwardIterator __result = __first;

      ++__first;

      for (; __first != __last; ++__first)

        if (!__pred(__first))

          {

            *__result = _GLIBCXX_MOVE(*__first);

            ++__result;

          }

      return __result;

    }

  /**

   *  @brief Remove elements from a sequence.

   *  @ingroup mutating_algorithms

   *  @param  __first  An input iterator.

   *  @param  __last   An input iterator.

   *  @param  __value  The value to be removed.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  All elements equal to @p __value are removed from the range

   *  @p [__first,__last).

   *

   *  remove() is stable, so the relative order of elements that are

   *  not removed is unchanged.

   *

   *  Elements between the end of the resulting sequence and @p __last

   *  are still present, but their value is unspecified.

  */

  template<typename _ForwardIterator, typename _Tp>

    inline _ForwardIterator

    remove(_ForwardIterator __first, _ForwardIterator __last,

	   const _Tp& __value)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_function_requires(_EqualOpConcept<

	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__remove_if(__first, __last,

		__gnu_cxx::__ops::__iter_equals_val(__value));

    }

  /**

   *  @brief Remove elements from a sequence using a predicate.

   *  @ingroup mutating_algorithms

   *  @param  __first  A forward iterator.

   *  @param  __last   A forward iterator.

   *  @param  __pred   A predicate.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  All elements for which @p __pred returns true are removed from the range

   *  @p [__first,__last).

   *

   *  remove_if() is stable, so the relative order of elements that are

   *  not removed is unchanged.

   *

   *  Elements between the end of the resulting sequence and @p __last

   *  are still present, but their value is unspecified.

  */

  template<typename _ForwardIterator, typename _Predicate>

    inline _ForwardIterator

    remove_if(_ForwardIterator __first, _ForwardIterator __last,

	      _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__remove_if(__first, __last,

			      __gnu_cxx::__ops::__pred_iter(__pred));

    }

  template<typename _ForwardIterator, typename _BinaryPredicate>

    _ForwardIterator

    __adjacent_find(_ForwardIterator __first, _ForwardIterator __last,

		    _BinaryPredicate __binary_pred)

    {

      if (__first == __last)

	return __last;

      _ForwardIterator __next = __first;

      while (++__next != __last)

	{

	  if (__binary_pred(__first, __next))

	    return __first;

	  __first = __next;

	}

      return __last;

    }

  template<typename _ForwardIterator, typename _BinaryPredicate>

    _ForwardIterator

    __unique(_ForwardIterator __first, _ForwardIterator __last,

	     _BinaryPredicate __binary_pred)

    {

      // Skip the beginning, if already unique.

      __first = std::__adjacent_find(__first, __last, __binary_pred);

      if (__first == __last)

	return __last;

      // Do the real copy work.

      _ForwardIterator __dest = __first;

      ++__first;

      while (++__first != __last)

	if (!__binary_pred(__dest, __first))

	  *++__dest = _GLIBCXX_MOVE(*__first);

      return ++__dest;

    }

  /**

   *  @brief Remove consecutive duplicate values from a sequence.

   *  @ingroup mutating_algorithms

   *  @param  __first  A forward iterator.

   *  @param  __last   A forward iterator.

   *  @return  An iterator designating the end of the resulting sequence.

   *

   *  Removes all but the first element from each group of consecutive

   *  values that compare equal.

   *  unique() is stable, so the relative order of elements that are

   *  not removed is unchanged.

   *  Elements between the end of the resulting sequence and @p __last

   *  are still present, but their value is unspecified.

  */

  template<typename _ForwardIterator>

    inline _ForwardIterator

    unique(_ForwardIterator __first, _ForwardIterator __last)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_function_requires(_EqualityComparableConcept<

		     typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__unique(__first, __last,

			   __gnu_cxx::__ops::__iter_equal_to_iter());

    }

  /**

   *  @brief Remove consecutive values from a sequence using a predicate.

   *  @ingroup mutating_algorithms

   *  @param  __first        A forward iterator.

   *  @param  __last         A forward iterator.

   *  @param  __binary_pred  A binary predicate.

   *  @return  An iterator designating the end of the resulting sequence.

   *

   *  Removes all but the first element from each group of consecutive

   *  values for which @p __binary_pred returns true.

   *  unique() is stable, so the relative order of elements that are

   *  not removed is unchanged.

   *  Elements between the end of the resulting sequence and @p __last

   *  are still present, but their value is unspecified.

  */

  template<typename _ForwardIterator, typename _BinaryPredicate>

    inline _ForwardIterator

    unique(_ForwardIterator __first, _ForwardIterator __last,

           _BinaryPredicate __binary_pred)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,

		typename iterator_traits<_ForwardIterator>::value_type,

		typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__unique(__first, __last,

			   __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));

    }

  /**

   *  This is an uglified

   *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,

   *              _BinaryPredicate)

   *  overloaded for forward iterators and output iterator as result.

  */

  template<typename _ForwardIterator, typename _OutputIterator,

	   typename _BinaryPredicate>

    _OutputIterator

    __unique_copy(_ForwardIterator __first, _ForwardIterator __last,

		  _OutputIterator __result, _BinaryPredicate __binary_pred,

		  forward_iterator_tag, output_iterator_tag)

    {

      // concept requirements -- iterators already checked

      __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,

	  typename iterator_traits<_ForwardIterator>::value_type,

	  typename iterator_traits<_ForwardIterator>::value_type>)

      _ForwardIterator __next = __first;

      *__result = *__first;

      while (++__next != __last)

	if (!__binary_pred(__first, __next))

	  {

	    __first = __next;

	    *++__result = *__first;

	  }

      return ++__result;

    }

  /**

   *  This is an uglified

   *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,

   *              _BinaryPredicate)

   *  overloaded for input iterators and output iterator as result.

  */

  template<typename _InputIterator, typename _OutputIterator,

	   typename _BinaryPredicate>

    _OutputIterator

    __unique_copy(_InputIterator __first, _InputIterator __last,

		  _OutputIterator __result, _BinaryPredicate __binary_pred,

		  input_iterator_tag, output_iterator_tag)

    {

      // concept requirements -- iterators already checked

      __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,

	  typename iterator_traits<_InputIterator>::value_type,

	  typename iterator_traits<_InputIterator>::value_type>)

      typename iterator_traits<_InputIterator>::value_type __value = *__first;

      *__result = __value;

      while (++__first != __last)

	if (!__binary_pred(__first, __value))

	  {

	    __value = *__first;

	    *++__result = __value;

	  }

      return ++__result;

    }

  /**

   *  This is an uglified

   *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,

   *              _BinaryPredicate)

   *  overloaded for input iterators and forward iterator as result.

  */

  template<typename _InputIterator, typename _ForwardIterator,

	   typename _BinaryPredicate>

    _ForwardIterator

    __unique_copy(_InputIterator __first, _InputIterator __last,

		  _ForwardIterator __result, _BinaryPredicate __binary_pred,

		  input_iterator_tag, forward_iterator_tag)

    {

      // concept requirements -- iterators already checked

      __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,

	  typename iterator_traits<_ForwardIterator>::value_type,

	  typename iterator_traits<_InputIterator>::value_type>)

      *__result = *__first;

      while (++__first != __last)

	if (!__binary_pred(__result, __first))

	  *++__result = *__first;

      return ++__result;

    }

  /**

   *  This is an uglified reverse(_BidirectionalIterator,

   *                              _BidirectionalIterator)

   *  overloaded for bidirectional iterators.

  */

  template<typename _BidirectionalIterator>

    void

    __reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,

	      bidirectional_iterator_tag)

    {

      while (true)

	if (__first == __last || __first == --__last)

	  return;

	else

	  {

	    std::iter_swap(__first, __last);

	    ++__first;

	  }

    }

  /**

   *  This is an uglified reverse(_BidirectionalIterator,

   *                              _BidirectionalIterator)

   *  overloaded for random access iterators.

  */

  template<typename _RandomAccessIterator>

    void

    __reverse(_RandomAccessIterator __first, _RandomAccessIterator __last,

	      random_access_iterator_tag)

    {

      if (__first == __last)

	return;

      --__last;

      while (__first < __last)

	{

	  std::iter_swap(__first, __last);

	  ++__first;

	  --__last;

	}

    }

  /**

   *  @brief Reverse a sequence.

   *  @ingroup mutating_algorithms

   *  @param  __first  A bidirectional iterator.

   *  @param  __last   A bidirectional iterator.

   *  @return   reverse() returns no value.

   *

   *  Reverses the order of the elements in the range @p [__first,__last),

   *  so that the first element becomes the last etc.

   *  For every @c i such that @p 0<=i<=(__last-__first)/2), @p reverse()

   *  swaps @p *(__first+i) and @p *(__last-(i+1))

  */

  template<typename _BidirectionalIterator>

    inline void

    reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<

				  _BidirectionalIterator>)

      __glibcxx_requires_valid_range(__first, __last);

      std::__reverse(__first, __last, std::__iterator_category(__first));

    }

  /**

   *  @brief Copy a sequence, reversing its elements.

   *  @ingroup mutating_algorithms

   *  @param  __first   A bidirectional iterator.

   *  @param  __last    A bidirectional iterator.

   *  @param  __result  An output iterator.

   *  @return  An iterator designating the end of the resulting sequence.

   *

   *  Copies the elements in the range @p [__first,__last) to the

   *  range @p [__result,__result+(__last-__first)) such that the

   *  order of the elements is reversed.  For every @c i such that @p

   *  0<=i<=(__last-__first), @p reverse_copy() performs the

   *  assignment @p *(__result+(__last-__first)-1-i) = *(__first+i).

   *  The ranges @p [__first,__last) and @p

   *  [__result,__result+(__last-__first)) must not overlap.

  */

  template<typename _BidirectionalIterator, typename _OutputIterator>

    _OutputIterator

    reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last,

		 _OutputIterator __result)

    {

      // concept requirements

      __glibcxx_function_requires(_BidirectionalIteratorConcept<

				  _BidirectionalIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

		typename iterator_traits<_BidirectionalIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      while (__first != __last)

	{

	  --__last;

	  *__result = *__last;

	  ++__result;

	}

      return __result;

    }

  /**

   *  This is a helper function for the rotate algorithm specialized on RAIs.

   *  It returns the greatest common divisor of two integer values.

  */

  template<typename _EuclideanRingElement>

    _EuclideanRingElement

    __gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)

    {

      while (__n != 0)

	{

	  _EuclideanRingElement __t = __m % __n;

	  __m = __n;

	  __n = __t;

	}

      return __m;

    }

  /// This is a helper function for the rotate algorithm.

  template<typename _ForwardIterator>

    void

    __rotate(_ForwardIterator __first,

	     _ForwardIterator __middle,

	     _ForwardIterator __last,

	     forward_iterator_tag)

    {

      if (__first == __middle || __last  == __middle)

	return;

      _ForwardIterator __first2 = __middle;

      do

	{

	  std::iter_swap(__first, __first2);

	  ++__first;

	  ++__first2;

	  if (__first == __middle)

	    __middle = __first2;

	}

      while (__first2 != __last);

      __first2 = __middle;

      while (__first2 != __last)

	{

	  std::iter_swap(__first, __first2);

	  ++__first;

	  ++__first2;

	  if (__first == __middle)

	    __middle = __first2;

	  else if (__first2 == __last)

	    __first2 = __middle;

	}

    }

   /// This is a helper function for the rotate algorithm.

  template<typename _BidirectionalIterator>

    void

    __rotate(_BidirectionalIterator __first,

	     _BidirectionalIterator __middle,

	     _BidirectionalIterator __last,

	      bidirectional_iterator_tag)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<

				  _BidirectionalIterator>)

      if (__first == __middle || __last  == __middle)

	return;

      std::__reverse(__first,  __middle, bidirectional_iterator_tag());

      std::__reverse(__middle, __last,   bidirectional_iterator_tag());

      while (__first != __middle && __middle != __last)

	{

	  std::iter_swap(__first, --__last);

	  ++__first;

	}

      if (__first == __middle)

	std::__reverse(__middle, __last,   bidirectional_iterator_tag());

      else

	std::__reverse(__first,  __middle, bidirectional_iterator_tag());

    }

  /// This is a helper function for the rotate algorithm.

  template<typename _RandomAccessIterator>

    void

    __rotate(_RandomAccessIterator __first,

	     _RandomAccessIterator __middle,

	     _RandomAccessIterator __last,

	     random_access_iterator_tag)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<

				  _RandomAccessIterator>)

      if (__first == __middle || __last  == __middle)

	return;

      typedef typename iterator_traits<_RandomAccessIterator>::difference_type

	_Distance;

      typedef typename iterator_traits<_RandomAccessIterator>::value_type

	_ValueType;

      _Distance __n = __last   - __first;

      _Distance __k = __middle - __first;

      if (__k == __n - __k)

	{

	  std::swap_ranges(__first, __middle, __middle);

	  return;

	}

      _RandomAccessIterator __p = __first;

      for (;;)

	{

	  if (__k < __n - __k)

	    {

	      if (__is_pod(_ValueType) && __k == 1)

		{

		  _ValueType __t = _GLIBCXX_MOVE(*__p);

		  _GLIBCXX_MOVE3(__p + 1, __p + __n, __p);

		  *(__p + __n - 1) = _GLIBCXX_MOVE(__t);

		  return;

		}

	      _RandomAccessIterator __q = __p + __k;

	      for (_Distance __i = 0; __i < __n - __k; ++ __i)

		{

		  std::iter_swap(__p, __q);

		  ++__p;

		  ++__q;

		}

	      __n %= __k;

	      if (__n == 0)

		return;

	      std::swap(__n, __k);

	      __k = __n - __k;

	    }

	  else

	    {

	      __k = __n - __k;

	      if (__is_pod(_ValueType) && __k == 1)

		{

		  _ValueType __t = _GLIBCXX_MOVE(*(__p + __n - 1));

		  _GLIBCXX_MOVE_BACKWARD3(__p, __p + __n - 1, __p + __n);

		  *__p = _GLIBCXX_MOVE(__t);

		  return;

		}

	      _RandomAccessIterator __q = __p + __n;

	      __p = __q - __k;

	      for (_Distance __i = 0; __i < __n - __k; ++ __i)

		{

		  --__p;

		  --__q;

		  std::iter_swap(__p, __q);

		}

	      __n %= __k;

	      if (__n == 0)

		return;

	      std::swap(__n, __k);

	    }

	}

    }

  /**

   *  @brief Rotate the elements of a sequence.

   *  @ingroup mutating_algorithms

   *  @param  __first   A forward iterator.

   *  @param  __middle  A forward iterator.

   *  @param  __last    A forward iterator.

   *  @return  Nothing.

   *

   *  Rotates the elements of the range @p [__first,__last) by 

   *  @p (__middle - __first) positions so that the element at @p __middle

   *  is moved to @p __first, the element at @p __middle+1 is moved to

   *  @p __first+1 and so on for each element in the range

   *  @p [__first,__last).

   *

   *  This effectively swaps the ranges @p [__first,__middle) and

   *  @p [__middle,__last).

   *

   *  Performs

   *   @p *(__first+(n+(__last-__middle))%(__last-__first))=*(__first+n)

   *  for each @p n in the range @p [0,__last-__first).

  */

  template<typename _ForwardIterator>

    inline void

    rotate(_ForwardIterator __first, _ForwardIterator __middle,

	   _ForwardIterator __last)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_requires_valid_range(__first, __middle);

      __glibcxx_requires_valid_range(__middle, __last);

      std::__rotate(__first, __middle, __last,

		    std::__iterator_category(__first));

    }

  /**

   *  @brief Copy a sequence, rotating its elements.

   *  @ingroup mutating_algorithms

   *  @param  __first   A forward iterator.

   *  @param  __middle  A forward iterator.

   *  @param  __last    A forward iterator.

   *  @param  __result  An output iterator.

   *  @return   An iterator designating the end of the resulting sequence.

   *

   *  Copies the elements of the range @p [__first,__last) to the

   *  range beginning at @result, rotating the copied elements by 

   *  @p (__middle-__first) positions so that the element at @p __middle

   *  is moved to @p __result, the element at @p __middle+1 is moved

   *  to @p __result+1 and so on for each element in the range @p

   *  [__first,__last).

   *

   *  Performs 

   *  @p *(__result+(n+(__last-__middle))%(__last-__first))=*(__first+n)

   *  for each @p n in the range @p [0,__last-__first).

  */

  template<typename _ForwardIterator, typename _OutputIterator>

    inline _OutputIterator

    rotate_copy(_ForwardIterator __first, _ForwardIterator __middle,

                _ForwardIterator __last, _OutputIterator __result)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

		typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __middle);

      __glibcxx_requires_valid_range(__middle, __last);

      return std::copy(__first, __middle,

                       std::copy(__middle, __last, __result));

    }

  /// This is a helper function...

  template<typename _ForwardIterator, typename _Predicate>

    _ForwardIterator

    __partition(_ForwardIterator __first, _ForwardIterator __last,

		_Predicate __pred, forward_iterator_tag)

    {

      if (__first == __last)

	return __first;

      while (__pred(*__first))

	if (++__first == __last)

	  return __first;

      _ForwardIterator __next = __first;

      while (++__next != __last)

	if (__pred(*__next))

	  {

	    std::iter_swap(__first, __next);

	    ++__first;

	  }

      return __first;

    }

  /// This is a helper function...

  template<typename _BidirectionalIterator, typename _Predicate>

    _BidirectionalIterator

    __partition(_BidirectionalIterator __first, _BidirectionalIterator __last,

		_Predicate __pred, bidirectional_iterator_tag)

    {

      while (true)

	{

	  while (true)

	    if (__first == __last)

	      return __first;

	    else if (__pred(*__first))

	      ++__first;

	    else

	      break;

	  --__last;

	  while (true)

	    if (__first == __last)

	      return __first;

	    else if (!bool(__pred(*__last)))

	      --__last;

	    else

	      break;

	  std::iter_swap(__first, __last);

	  ++__first;

	}

    }

  // partition

  /// This is a helper function...

  /// Requires __len != 0 and !__pred(*__first),

  /// same as __stable_partition_adaptive.

  template<typename _ForwardIterator, typename _Predicate, typename _Distance>

    _ForwardIterator

    __inplace_stable_partition(_ForwardIterator __first,

			       _Predicate __pred, _Distance __len)

    {

      if (__len == 1)

	return __first;

      _ForwardIterator __middle = __first;

      std::advance(__middle, __len / 2);

      _ForwardIterator __left_split =

	std::__inplace_stable_partition(__first, __pred, __len / 2);

      // Advance past true-predicate values to satisfy this

      // function's preconditions.

      _Distance __right_len = __len - __len / 2;

      _ForwardIterator __right_split =

	std::__find_if_not_n(__middle, __right_len, __pred);

      if (__right_len)

	__right_split = std::__inplace_stable_partition(__middle,

							__pred,

							__right_len);

      std::rotate(__left_split, __middle, __right_split);

      std::advance(__left_split, std::distance(__middle, __right_split));

      return __left_split;

    }

  /// This is a helper function...

  /// Requires __first != __last and !__pred(__first)

  /// and __len == distance(__first, __last).

  ///

  /// !__pred(__first) allows us to guarantee that we don't

  /// move-assign an element onto itself.

  template<typename _ForwardIterator, typename _Pointer, typename _Predicate,

	   typename _Distance>

    _ForwardIterator

    __stable_partition_adaptive(_ForwardIterator __first,

				_ForwardIterator __last,

				_Predicate __pred, _Distance __len,

				_Pointer __buffer,

				_Distance __buffer_size)

    {

      if (__len <= __buffer_size)

	{

	  _ForwardIterator __result1 = __first;

	  _Pointer __result2 = __buffer;

	  // The precondition guarantees that !__pred(__first), so

	  // move that element to the buffer before starting the loop.

	  // This ensures that we only call __pred once per element.

	  *__result2 = _GLIBCXX_MOVE(*__first);

	  ++__result2;

	  ++__first;

	  for (; __first != __last; ++__first)

	    if (__pred(__first))

	      {

		*__result1 = _GLIBCXX_MOVE(*__first);

		++__result1;

	      }

	    else

	      {

		*__result2 = _GLIBCXX_MOVE(*__first);

		++__result2;

	      }

	  _GLIBCXX_MOVE3(__buffer, __result2, __result1);

	  return __result1;

	}

      else

	{

	  _ForwardIterator __middle = __first;

	  std::advance(__middle, __len / 2);

	  _ForwardIterator __left_split =

	    std::__stable_partition_adaptive(__first, __middle, __pred,

					     __len / 2, __buffer,

					     __buffer_size);

	  // Advance past true-predicate values to satisfy this

	  // function's preconditions.

	  _Distance __right_len = __len - __len / 2;

	  _ForwardIterator __right_split =

	    std::__find_if_not_n(__middle, __right_len, __pred);

	  if (__right_len)

	    __right_split =

	      std::__stable_partition_adaptive(__right_split, __last, __pred,

					       __right_len,

					       __buffer, __buffer_size);

	  std::rotate(__left_split, __middle, __right_split);

	  std::advance(__left_split, std::distance(__middle, __right_split));

	  return __left_split;

	}

    }

  template<typename _ForwardIterator, typename _Predicate>

    _ForwardIterator

    __stable_partition(_ForwardIterator __first, _ForwardIterator __last,

		       _Predicate __pred)

    {

      __first = std::__find_if_not(__first, __last, __pred);

      if (__first == __last)

	return __first;

      typedef typename iterator_traits<_ForwardIterator>::value_type

	_ValueType;

      typedef typename iterator_traits<_ForwardIterator>::difference_type

	_DistanceType;

      _Temporary_buffer<_ForwardIterator, _ValueType> __buf(__first, __last);

      if (__buf.size() > 0)

	return

	  std::__stable_partition_adaptive(__first, __last, __pred,

					   _DistanceType(__buf.requested_size()),

					   __buf.begin(),

					   _DistanceType(__buf.size()));

      else

	return

	  std::__inplace_stable_partition(__first, __pred,

					  _DistanceType(__buf.requested_size()));

    }

  /**

   *  @brief Move elements for which a predicate is true to the beginning

   *         of a sequence, preserving relative ordering.

   *  @ingroup mutating_algorithms

   *  @param  __first   A forward iterator.

   *  @param  __last    A forward iterator.

   *  @param  __pred    A predicate functor.

   *  @return  An iterator @p middle such that @p __pred(i) is true for each

   *  iterator @p i in the range @p [first,middle) and false for each @p i

   *  in the range @p [middle,last).

   *

   *  Performs the same function as @p partition() with the additional

   *  guarantee that the relative ordering of elements in each group is

   *  preserved, so any two elements @p x and @p y in the range

   *  @p [__first,__last) such that @p __pred(x)==__pred(y) will have the same

   *  relative ordering after calling @p stable_partition().

  */

  template<typename _ForwardIterator, typename _Predicate>

    inline _ForwardIterator

    stable_partition(_ForwardIterator __first, _ForwardIterator __last,

		     _Predicate __pred)

    {

      // concept requirements

      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<

				  _ForwardIterator>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__stable_partition(__first, __last,

				     __gnu_cxx::__ops::__pred_iter(__pred));

    }

  /// This is a helper function for the sort routines.

  template<typename _RandomAccessIterator, typename _Compare>

    void

    __heap_select(_RandomAccessIterator __first,

		  _RandomAccessIterator __middle,

		  _RandomAccessIterator __last, _Compare __comp)

    {

      std::__make_heap(__first, __middle, __comp);

      for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)

	if (__comp(__i, __first))

	  std::__pop_heap(__first, __middle, __i, __comp);

    }

  // partial_sort

  template<typename _InputIterator, typename _RandomAccessIterator,

	   typename _Compare>

    _RandomAccessIterator

    __partial_sort_copy(_InputIterator __first, _InputIterator __last,

			_RandomAccessIterator __result_first,

			_RandomAccessIterator __result_last,

			_Compare __comp)

    {

      typedef typename iterator_traits<_InputIterator>::value_type

	_InputValueType;

      typedef iterator_traits<_RandomAccessIterator> _RItTraits;

      typedef typename _RItTraits::difference_type _DistanceType;

      if (__result_first == __result_last)

	return __result_last;

      _RandomAccessIterator __result_real_last = __result_first;

      while (__first != __last && __result_real_last != __result_last)

	{

	  *__result_real_last = *__first;

	  ++__result_real_last;

	  ++__first;

	}

      std::__make_heap(__result_first, __result_real_last, __comp);

      while (__first != __last)

	{

	  if (__comp(__first, __result_first))

	    std::__adjust_heap(__result_first, _DistanceType(0),

			       _DistanceType(__result_real_last

					     - __result_first),

			       _InputValueType(*__first), __comp);

	  ++__first;

	}

      std::__sort_heap(__result_first, __result_real_last, __comp);

      return __result_real_last;

    }

  /**

   *  @brief Copy the smallest elements of a sequence.

   *  @ingroup sorting_algorithms

   *  @param  __first   An iterator.

   *  @param  __last    Another iterator.

   *  @param  __result_first   A random-access iterator.

   *  @param  __result_last    Another random-access iterator.

   *  @return   An iterator indicating the end of the resulting sequence.

   *

   *  Copies and sorts the smallest N values from the range @p [__first,__last)

   *  to the range beginning at @p __result_first, where the number of

   *  elements to be copied, @p N, is the smaller of @p (__last-__first) and

   *  @p (__result_last-__result_first).

   *  After the sort if @e i and @e j are iterators in the range

   *  @p [__result_first,__result_first+N) such that i precedes j then

   *  *j<*i is false.

   *  The value returned is @p __result_first+N.

  */

  template<typename _InputIterator, typename _RandomAccessIterator>

    inline _RandomAccessIterator

    partial_sort_copy(_InputIterator __first, _InputIterator __last,

		      _RandomAccessIterator __result_first,

		      _RandomAccessIterator __result_last)

    {

      typedef typename iterator_traits<_InputIterator>::value_type

	_InputValueType;

      typedef typename iterator_traits<_RandomAccessIterator>::value_type

	_OutputValueType;

      typedef typename iterator_traits<_RandomAccessIterator>::difference_type

	_DistanceType;

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_ConvertibleConcept<_InputValueType,

				  _OutputValueType>)

      __glibcxx_function_requires(_LessThanOpConcept<_InputValueType,