[백준] 10828 스택

[백준] 10828 스택

• https://www.acmicpc.net/problem/10828

#include <iostream>
#include <string>
#include <stack>
using namespace std;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);

	int n;
	cin >> n;

	stack<int> st;
	while (n--) {
		string op;
		cin >> op;
		if (op == "push") {
			int x;
			cin >> x;
			st.push(x);
		}
		else if (op == "pop") {
			if (st.empty()) cout << "-1\n";
			else {
				cout << st.top()<<"\n";
				st.pop();
			}
		}
		else if (op == "size") {
			cout << st.size() << "\n";
		}
		else if (op == "empty") {
			cout << st.empty()<<"\n";
		}
		else if (op == "top") {
			if (st.empty()) cout << "-1\n";
			else cout << st.top() << "\n";
		}
	}

	return 0;
}