using System;

public class Program

{ // no code above 

    // method here 

    public static void Main()

    {

        Console.WriteLine("This program will calculate the GCD of two numbers. Please Enter Your two Values");

            long num1 = long.Parse(Console.ReadLine());

            long num2 = long.Parse(Console.ReadLine());

            long ans = GCD(num1, num2);

            Console.WriteLine(ans);

    } 

    // method here 

static private long GCD(long a, long b)

        { long remainder;

        do

        {remainder = a%b;

            if(remainder !=0)

            {a = b;

             b = remainder;

            }

        } while(remainder >0);

        return b;

        }

}

​