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.IOException;
import java.io.InputStreamReader;
import java.util.Collections;
import java.util.PriorityQueue;

class Main{
	public static void main(String[] args)throws NumberFormatException, IOException{
//		System.out.println(" ");
	    InputStreamReader input = new InputStreamReader (System. in);
	    BufferedReader buffer = new BufferedReader(input);

	    PriorityQueue<Integer> quere = new PriorityQueue<Integer> (Collections.reverseOrder());
	    while(true){
		    String read = buffer.readLine();
		    String[] scan = read.split(" ");
	    	if(scan[0].equals("insert")){
	    		quere.add(Integer.parseInt(scan[1]));
	    	}
	    	if(scan[0].equals("extract")){
	    		System.out.println(quere.poll());
	    	}
	    	if(scan[0].equals("end")){
	    		break;
	    	}
	    }
	}
}