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.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.Scanner;
import java.util.PriorityQueue;

class Main {
    public static void main (String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String operation;
        PriorityQueue<Integer> queue = new PriorityQueue<Integer>();
        StringBuilder sb = new StringBuilder("");
        while (true) {
            operation = br.readLine();
            if (operation.charAt(0) == 'i') {
                queue.add(Integer.parseInt(operation.substring(7)) * -1);
            } else if (operation.charAt(1) == 'x') {
                sb.append(queue.poll() * -1);
                sb.append('\n');
            } else {
                break;
            }
        }
        System.out.print(sb);
    }
}