题目链接：模拟队列

#include <iostream>

using namespace std;

const int N = 100010;

int m;
int q[N], hh, tt = -1;

int main()
{
    cin >> m;
    while(m--)
    {
        string op;
        int x;
        cin >> op;
        if(op == "push")
        {
            cin >> x;
            q[++tt] = x;
        }
        else if(op == "pop") hh++;
        else if(op == "empty") cout << (hh <= tt? "NO": "YES") << endl;
        else cout << q[hh] << endl;
    }
    return 0;
}