#include <iostream>
#include <string>


using namespace std;

int GetNumber(string prompt);
int GCD(int a, int b);

int main() {
    int a,b;

    a = GetNumber("Enter a positive integer => ");
    b = GetNumber("Enter a second positive integer => ");
    cout << "The GCD of  " << a << " and " << b << " is " << GCD(a,b) << endl;

    return 0;
}

int GetNumber(string prompt) {
   int a;
   cout << prompt;
   cin >> a;

   return a;
}

int GCD(int a, int b) {
    if (b > a) {
       return GCD(b,a);
    } else if (b == 0) {
       return a;
    } else {
       return GCD(b, a%b);
    }
}