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diff --git a/libstdc++-v3/testsuite/ext/pb_ds/example/basic_multiset.cc b/libstdc++-v3/testsuite/ext/pb_ds/example/basic_multiset.cc
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+// -*- C++ -*-
+
+// Copyright (C) 2005, 2006, 2009 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.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+
+// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
+
+// Permission to use, copy, modify, sell, and distribute this software
+// is hereby granted without fee, provided that the above copyright
+// notice appears in all copies, and that both that copyright notice
+// and this permission notice appear in supporting documentation. None
+// of the above authors, nor IBM Haifa Research Laboratories, make any
+// representation about the suitability of this software for any
+// purpose. It is provided "as is" without express or implied
+// warranty.
+
+/**
+ * @file basic_multiset_example.cpp
+ * A basic example showing how to use multisets.
+ */
+
+
+// This example shows how to use "multisets".
+
+// In this example we build a very simple priority queue that also can
+// be queried if an entry contains (i.e., it is slightly similar to an
+// associative container as well as a priority queue). The priority
+// queue adapts a "multiset".
+
+// (Note that there are more efficient ways for implementing this than
+// by adapting an associative container. This is just an example for
+// "multisets".)
+
+#include <iostream>
+#include <cassert>
+#include <ext/pb_ds/assoc_container.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+// A simple priority queue that also supports an "contains" query.
+class contains_pq
+{
+public:
+  // Pushes an integer.
+  void
+  push(int i);
+
+  // Pops the largest integer and returns it.
+  int
+  pop();
+
+  // Returns true iff i is contained in the container.
+  bool
+  contains(int i) const
+  { return m_tree.find(i) != m_tree.end(); }
+
+  // Returns true iff empty.
+  bool
+  empty() const
+  { return m_tree.empty(); }
+
+private:
+  // This is the container type we adapt - a "multiset".
+  // It maps each integer to the number of times it logically appears.
+  typedef
+  tree<
+  int,
+  size_t,
+  greater<
+  int> >
+  tree_t;
+
+private:
+  tree_t m_tree;
+};
+
+void
+contains_pq::
+push(int i)
+{
+  // To push i, we insert to the "multiset" that i appears 0 times
+  // (which is a no-op if i already is contained), then increment the
+  // number of times i is contained by 1.
+  ++m_tree.insert(make_pair(i, 0)).first->second;
+}
+
+int
+contains_pq::
+pop()
+{
+  assert(!empty());
+
+  // The element we need to pop must be the first one, since tree_t is
+  // an ordered container.
+  tree_t::iterator it = m_tree.begin();
+
+  const int i = it->first;
+
+  // Decrease the number of times the popped element appears in the
+  // container object. If it is 0 - we erase it.
+  if (--it->second == 0)
+    m_tree.erase(it);
+
+  return i;
+}
+
+int main()
+{
+  contains_pq cpq;
+
+  // First we push some elements.
+  cpq.push(4);
+  cpq.push(3);
+  cpq.push(2);
+  cpq.push(1);
+  cpq.push(4);
+
+  // Note that logically, 4 appears 2 times, and each of 1, 2, and 3
+  // appear once.
+  assert(cpq.contains(4));
+  assert(cpq.contains(3));
+  assert(cpq.contains(2));
+  assert(cpq.contains(1));
+
+  // Now pop the topmost element - it should be 4.
+  assert(cpq.pop() == 4);
+
+  // Now logically, each of 1, 2, 3, and 4 appear once.
+  assert(cpq.contains(4));
+
+  // We pop the topmost element - it should be 4.
+  assert(cpq.pop() == 4);
+
+  // 4 should not be contained any more.
+  assert(!cpq.contains(4));
+
+  assert(cpq.contains(3));
+  assert(cpq.contains(2));
+  assert(cpq.contains(1));
+
+  assert(cpq.pop() == 3);
+  assert(cpq.pop() == 2);
+  assert(cpq.pop() == 1);
+
+  assert(cpq.empty());
+
+  return 0;
+}
+