运用queue解决本题的题解

运用queue解决代码：

#include <iostream>
#include <queue>
using namespace std;

int main() {
    int n;
    cin >> n;
    queue<int> q;
    
    while (n--) {
        int op;
        cin >> op;
        
        if (op == 1) {
            int x;
            cin >> x;
            q.push(x);
        }
        else if (op == 2) {
            if (q.empty()) {
                cout << "impossible!" << endl;
            }
            else {
                q.pop();
            }
        }
        else if (op == 3) {
            if (q.empty()) {
                cout << "impossible!" << endl;
            }
            else {
                cout << q.front() << endl;
            }
        }
    }
    
    return 0;
}