#include <iostream>
#include <deque>
using namespace std;

deque < int > q[100005];

int main(){
    int n;
    cin >> n;
    while(n--){
        string s;
        cin >> s;
        int a,x;
        cin >> a;
        if(s == "push_back") cin >> x,q[a].push_back(x);
        if(s == "pop_back" && q[a].size()) q[a].pop_back();
        if(s == "push_front") cin >> x,q[a].push_front(x);
        if(s == "pop_front" && q[a].size()) q[a].pop_front();
        if(s == "size") cout << q[a].size() << '\n';
        if(s == "front" && q[a].size()) cout << q[a].front() << '\n';
        if(s == "back" && q[a].size()) cout << q[a].back() << '\n';
    }
    return 0;
}

RE on #19