/* A priority queue maintains a set of elements. The supported operations are
insertion and, depending on the type of the queue, retrieval and removal
of either the minimum or maximum element. Insertion and removal take
O(logn) time, and retrieval takes O(1) time. */
priority_queue<int> q;
q.push(3); // 3
q.push(5); // 3 5
q.push(7); // 3 5 7
q.push(2); // 2 3 5 7
cout << q.top() << "
"; // 7
q.pop();
cout << q.top() << "
"; // 5
q.pop();
q.push(6);
cout << q.top() << "
"; // 6
q.pop();