#include <iostream>
#include <deque>
using namespace std;
deque<int> a;
int main()
{
    int n;
    for (int i = 1;i <= n;i++)
    {
        string s;
        int num, sum;
        cin >> s;
        if (s == "pop_back")
        {
            cin >> num;
            if (!a.empty())
            {
                a.pop_back(num);
            }
        }
        else if (s == "push_back")
        {
            cin >> num >> sum;
            a.push_back(num, sum);
        }
        else if (s == "push_front")
        {
            cin >> num >> sum;
            a.push_front(num, sum);
        }
        else if (s == "pop_front")
        {
            cin >> num;
            if (!a.empty())
            {
                a.pop_front(num);
            }
        }
        else if (s == "size")
        {
            cout << a.size() << endl;
        }
        else if (s == "front")
        {
            cin >> num;
            if (!a.empty())
            {
                cout << a.front(num) << endl;
            }
        }
        else if (s == "back")
        {
            cin >> num;
            if (!a.empty())
            {
                cout << a.back(num) << endl;
            }
        }
    }
    return 0;
}