#include<bits/stdc++.h>
using namespace std;
const int N=4e5+10;
struct node{
    deque<string>dq;
}a[N];
int n,x;
str op,y;
signed main()
{
    cin>>n;
    while(n--)
	{
        cin>>op>>x;
        if(op=="push_back")
		{
            cin>>y;
            a[x].dq.push_back(y);
        }
        else if(op=="pop_back")
		{
            if(a[x].dq.size()!=0)
			{
                a[x].dq.pop_back();
            }
        }
        else if(op=="push_front")
		{
            cin>>y;
            a[x].dq.push_front(y);
        }
        else if(op=="pop_front")
		{
            if(a[x].dq.size()!=0)
			{
                a[x].dq.pop_front();
            }
        }
        else if(op=="size")
		{
            cout<<a[x].dq.size()<<"\n";
        }
        else if(op=="front")
		{
            if(a[x].dq.size()!=0)
			{
                cout<<a[x].dq.front()<<"\n";
            }
        }
        else if(op=="back")
		{
            if(a[x].dq.size()!=0)
			{
                cout<<a[x].dq.back()<<"\n";
            }
        }
    }
	return 0;
}