10828번 스택

#include <iostream>
#include <stack>
#include <string.h>
#include <string>

using namespace std;

void solve() {
	stack<int> stk;
	string command;
	int inputData;
	int commandLine;

	cin >> commandLine;

	for (int i = 0; i < commandLine; i++) {
		cin >> command;
		if (!command.compare("push")) {
			cin >> inputData;
			stk.push(inputData);
		}
		else if (!command.compare("pop")) {
			if (stk.size() == 0)
				cout << "-1" << endl;
			else {
				cout << stk.top() << endl;
				stk.pop();
			}
		}
		else if (!command.compare("size")) {
			cout << stk.size() << endl;
		}
		else if (!command.compare("empty")) {
			cout << stk.empty() << endl;
		}
		else if (!command.compare("top")) {
			if (stk.size() == 0)
				cout << "-1" << endl;
			else
				cout << stk.top() << endl;
		}
	}
}

int main() {
	solve();
	return 0;
}