#include<iostream>
#include<list>
using namespace std;
list <int> q[1000001];
int c,a,b;
string s;
int main(){
    cin>>c;
    while(c--){
        cin>>s;
        if(s=="push_back"){
            cin>>a>>b;
            q[a].push_back(b);
        }
        if(s=="pop_back"){
            cin>>a;
            if(!q[a].empty()) q[a].pop_back();
        }
        if(s=="push_front"){
            cin>>a>>b;
            q[a].push_front(b);
        }
        if(s=="pop_front"){
            cin>>a;
            if(!q[a].empty()) q[a].pop_front();
        }
        if(s=="size"){
            cin>>a;
            if(!q[a].empty()) cout<<q[a].size()<<endl;
        }
        if(s=="front"){
            cin>>a;
            if(!q[a].empty()) cout<<q[a].front()<<endl;
        }
        if(s=="back"){
            cin>>a;
            if(!q[a].empty()) cout<<q[a].back()<<endl;
        }
    }
}