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++11 (judge verdict: Accepted)

#include <iostream>
#include <queue>

int main()
{
	std::priority_queue<int> que;
	
	std::string buf;
	while (true) {
		getline(std::cin, buf);
		int sp_pos = buf.find(' ', 0);
		if (sp_pos>=0) {
			// insert
			int key = std::stoi(buf.substr(sp_pos+1));
			que.push(key);
		}
		else {
			std::string op = buf.substr(0, sp_pos);
			if (op == "end") break;
			else {
				// extract
				std::cout << que.top() << std::endl;
				que.pop();
			}
		}
	}
	
	return 0;
}