#include <iostream>
#include <queue>
#include <string>

using namespace std;

int main() {
    queue<int>p;
    int n;
    cin>>n;
    while(n--){
    	string g;
    	cin>>g;
    	int o;
    	if(g=="push"){
    		cin>>o;
    		p.push(o);
    	}else if(g=="pop"){
          p.pop();}
    else if(g=="front"){
       cout<<p.front()<<endl;}
   else if(g=="back"){
   	cout<<p.back()<<endl;
   }
}
}