#include<bits/stdc++.h>
using namespace std;
const int N=1e6+10;
list<long long> l[N];
int q;
string op;
int a,x;
int main(){
	cin>>q;
	while(q--){
		cin>>op;
		if(op=="push_back"){
			cin>>a>>x;
			l[a].push_back(x);
		}
		if(op=="pop_back"){
			cin>>a;
			if(!l[a].empty()) l[a].pop_back();
		}
		if(op=="push_front"){
			cin>>a>>x;
			l[a].push_front(x);
		}
		if(op=="pop_front"){
			cin>>a;
			if(!l[a].empty()) l[a].pop_front();
		}
		if(op=="size"){
			cin>>a;
			cout<<l[a].size()<<endl;
		}
		if(op=="front"){
			cin>>a;
			cout<<l[a].front()<<endl;
		}
		if(op=="back"){
			cin>>a;
			cout<<l[a].back()<<endl;
		}
	}
	return 0;
}