#![allow(unused_variables)]
fn main() {
    use std::collections::BinaryHeap;
    use std::cmp::Reverse;
    let mut heap = BinaryHeap::new();
    heap.push(Reverse(1));
    heap.push(Reverse(5));
    heap.push(Reverse(2));
    assert_eq!(heap.pop(), Some(Reverse(1)));
    assert_eq!(heap.pop(), Some(Reverse(2)));
    assert_eq!(heap.pop(), Some(Reverse(5)));
    assert_eq!(heap.pop(), None);
}