听灌佬多

#include <bits/stdc++.h>
using namespace std;
deque<int>dq[1000005];
int n;
string s;

int main() {
	cin >> n;
	while (n--) {
		cin >> s;
		int x, y;
		cin >> x;
		if (s == "pop_back") {
			dq[x].pop_back();
		} else if (s == "push_back") {
			cin >> y;
			dq[x].push_back(y);

		} else if (s == "push_front") {
			cin >> y;
			dq[x].push_front(y);
		} else if (s == "pop_front") {
			dq[x].pop_front ();
		} else if (s == "size") {
			if (dq[x].empty() == 0) {
				cout << dq[x].size() << endl;
			}
		} else if (s == "front") {
			if (dq[x].empty() == 0) {
				cout << dq[x].front() << endl;
			}
		} else if (s == "back") {
			if (dq[x].empty() == 0) {
				cout << dq[x].back() << endl;
			}
		}
	}

	return 0;
}