// 优先队列
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<queue>
#include<set>
using namespace std;

int main(){
priority_queue<int, vector<int>, less<int>> q;
priority_queue<int, vector<int>, greater<int>> p;
// priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> z;
// z.push({3, 1});
q.push(2);
q.push(4);

while(!q.empty()){
printf("%d\n", q.top());
q.pop();
    }

return 0;
}