#include <bits/stdc++.h>
using namespace std;
const int M=1e6+7;
int main()
{
	deque<long long>dq[M];
	string s;
	int q;
	cin>>q;
	while(q--)
	{
		int a,x;
		cin>>s;
		if(s=="push_back")
		{
			cin>>a>>x;
			dq[a].push_back(x);
		}
		if(s=="pop_back")
		{
			cin>>a;
			if(dq[a].size()!=0)
				dq[a].pop_back();
		}
		if(s=="push_front")
		{
			cin>>a>>x;
			dq[a].push_front(x);
		}
		if(s=="pop_front")
		{
			cin>>a;
			if(dq[a].size()!=0)
				dq[a].pop_front();
		}
		if(s=="size")
		{
			cin>>a;
			cout<<dq[a].size()<<endl;
		}
		if(s=="front")
		{
			cin>>a;
			if(dq[a].size()!=0)
				cout<<dq[a].front()<<endl;
		}
		if(s=="back")
		{
			cin>>a;
			if(dq[a].size()!=0)
				cout<<dq[a].back()<<endl;
		}
	}
 	return 0;
}