#include<bits/stdc++.h>
using namespace std;
deque<long long> q[5000];
int main()
{
	long long n;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		string s;
		cin>>s;
		long long a,b;
		cin>>a>>b;
		if(s=="push_back")
			q[a].push_back(b);
		else if(s=="pop_back")
		{
			if(!q[a].empty())
				q[a].pop_back();
			else
				continue;
		}
		else if(s=="push_front")
			q[a].push_front(b);
		else if(s=="pop_front")
		{
			if(!q[a].empty())
				q[a].pop_front();
			else
				continue;
		}
		else if(s=="size")
		{
			cout<<q[a].size()<<endl;
		}
		else if(s=="front")
		{
			if(!q[a].empty())
				cout<<q[a].front()<<endl;
			else
				continue;
		}
		else if(s=="back")
		{
			if(!q[a].empty())
				cout<<q[a].back()<<endl;
			else
				continue;
		}
	}
	return 0;
}