cau_truc_du_lieu_hang_doi_2.cpp

#include<bits/stdc++.h>
using namespace std;
int main(){
   long long t; cin >>t;
   cin.ignore();
    queue<long long> st1;
    while(t--){
        string s;
        getline(cin, s);
        stringstream ss(s);
        string x;
        ss >> x;
        long long x1;
        if(x == "PUSH"){ ss >> x1; st1.push(x1); }
        if(x ==  "POP" && st1.size() > 0 ){st1.pop();}
        if(x == "PRINTFRONT"){
            if(st1.size() == 0 ) cout<<"NONE"<<endl;
            else{
                vector<int> v;
                cout<<st1.front()<<endl;

            }
        }
    }
}