[백준]10828-스택(설명X)

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