using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter n");

        int n = int.Parse(Console.ReadLine());

        Console.WriteLine("Enter r");

        int r = int.Parse(Console.ReadLine());

        int value  = fact(n)/(fact(n-r) * fact(r));

        Console.WriteLine("Value of C(n,r) is {0} ", value);

    }

​

    static int fact(int n){

        int value=0;

        //cout<<"Hello";

        if(n==0 || n==1)

            return 1;

        else

            value =  n * fact(n-1);

            return value;

​

    }

​

}