Problem:
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Priority Queue

A priority queue is a data structure which maintains a set $S$ of elements, each of with an associated value (key), and supports the following operations:

$insert(S, k)$: insert an element $k$ into the set $S$

$extractMax(S)$: remove and return the element of $S$ with the largest key

Write a program which performs the $insert(S, k)$ and $extractMax(S)$ operations to a priority queue $S$.
The priority queue manages a set of integers, which are also keys for the priority.

Input

Multiple operations to the priority queue $S$ are given. Each operation is given by "insert $k$", "extract" or "end" in a line. Here, $k$ represents an integer element to be inserted to the priority queue.

The input ends with "end" operation.

Output

For each "extract" operation, print the element extracted from the priority queue $S$ in a line.

Constraints

The number of operations $\leq 2,000,000$

$0 \leq k \leq 2,000,000,000$

Sample Input 1

insert 8
insert 2
extract
insert 10
extract
insert 11
extract
extract
end

Sample Output 1

8
10
11
2

Solution in C++14 (judge verdict: Accepted)

#include <iostream>
#include <queue>
#include <string>
using namespace std;

void insert(priority_queue<int> &q, int k)
{
    q.push(k);
    return;
}

int extractMax(priority_queue<int> &q)
{
    if (q.empty())
    {
        return -1;
    }
    int max = q.top();
    q.pop();
    return max;
}

int main()
{
    string cmd;
    priority_queue<int> Q;

    while (cin >> cmd && cmd != "end")
    {
        if (cmd == "insert")
        {
            int k;
            cin >> k;
            insert(Q, k);
        }
        else if (cmd == "extract")
        {
            int result = extractMax(Q);
            printf("%d\n", result);
        }
    }
}