using System;
class Program
{
static int gcd(int a, int b) {
return b == 0 ? a : gcd(b, a % b);
}
static void Main(string[] args)
{
int a = 12, b = 20;
Console.WriteLine("The GCD (greatest common divisor) of {0} and {1} is: {2}", a, b, gcd(a, b));
}
}
/*
run:
The GCD (greatest common divisor) of 12 and 20 is: 4
*/