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 Rust (judge verdict: Accepted)

// ALDS1_9_C: Priority Queue

use std::collections::BinaryHeap;

fn main() {
    let mut b = BinaryHeap::new();

    loop {
        let mut s = String::new();
        std::io::stdin().read_line(&mut s).unwrap();
        let mut it = s.split_whitespace();
        let com = it.next().unwrap();
        if com == "end" {
            break;
        } 
        if com == "insert" {
            let x: i64 = it.next().unwrap().parse().ok().unwrap();
            b.push(x);
        } else {
            println!("{}", b.pop().unwrap());
        }
    }
}