[10828] 스택

#include <iostream>
#include <stack>
#include <string>
using namespace std;
int main()
{
	stack <int> st;
	string str;
	int testcase;
	cin >> testcase;
	for (int i = 0; i < testcase; i++)
	{
		cin >> str;
		if (str == "push")
		{
			int num;
			cin >> num;
			st.push(num);
		}
		else if (str == "pop")
		{
			if (!st.empty())
			{
				cout << st.top() << endl;
				st.pop();
			}
			else
				cout << "-1" << endl;
		}
		else if (str == "size")
		{
			cout << st.size() << endl;
		}
		else if (str == "empty")
		{
			if (st.empty())
				cout << "1" << endl;
			else
				cout << "0" << endl;
		}
		else if (str == "top")
		{
			if (!st.empty())
				cout << st.top() << endl;
			else
				cout << "-1" << endl;
		}
	}
	return 0;
}