#include <bits/stdc++.h>

using namespace std;
const int N = 1e5 + 10;
int q[N], hh, tt;
int main() {
    int n;
    cin >> n;
    while (n--) {
        string op;
        cin >> op;
        if (op == "push")
            cin >> q[tt++];
        else if (op == "empty")
            hh >= tt ? cout << "YES" << endl : cout << "NO" << endl;
        else if (op == "query")
            cout << q[hh] << endl;
        else
            hh++;
    }
    return 0;
}