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 JAVA (judge verdict: Accepted)

import java.util.Collections;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {

	private static final int BIG_NUM  = 2000000000;
	private static final int MOD  = 1000000007;

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		PriorityQueue<Integer> Q = new PriorityQueue<Integer>(1,Collections.reverseOrder());

		String order;
		StringBuilder ans = new StringBuilder();
		int value;

		while(true){

			order = scanner.next();

			if(order.equals("end")){
				break;
			}else if(order.equals("insert")){
				value = scanner.nextInt();
				Q.add(value);
			}else{ //extract
				ans.append(Integer.toString(Q.peek())).append("\n");
				Q.remove();
			}
		}
		System.out.printf(ans.toString());
	}
}