[10866] 덱

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