Простейший калькулятор с областью допустимых значений Z

#include <iostream>
using namespace std;
int main()
{
    int n, k;
    cin >> n >> k;
    cout << n << " + " << k << " = " << n + k << endl;
    cout << n << " - " << k << " = " << n - k << endl;
    cout << n << " * " << k << " = " << n * k << endl;
    cout << n << " / " << k << " = " << n / k << endl;
}