/*
LuoGu B3656 【模板】双端队列 1  
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 5;
list<ll> l[maxn];
string s;
ll a,q,x;
signed main()
{
	cin>>q;
	while(q--)
	{
		cin>>s;
		if(s == "push_back")
		{
			cin>>a>>x;
			l[a].push_back(x);
		}
		else if(s == "pop_back")
		{
			cin>>a;
			if(l[a].empty()) continue;
			else l[a].pop_back();
		}
		else if(s == "push_front")
		{
			cin>>a>>x;
			l[a].push_front(x);
		}
		else if(s == "pop_front")
		{
			cin>>a;
			if(l[a].empty()) continue;
			else l[a].pop_front();
		}
		else if(s == "size")
		{
			cin>>a;
			if(l[a].empty()) continue;
			else cout<<l[a].size()<<"\n";
		}
		else if(s == "front")
		{
			cin>>a;
			if(l[a].empty()) continue;
			else cout<<l[a].front()<<"\n";
		}
		else if(s == "back")
		{
			cin>>a;
			if(l[a].empty()) continue;
			else cout<<l[a].back()<<"\n";
		}
	}
	return 0;
}