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/* to calculate binomial coefficient of nCr.

nCr = n!/ r! (n-r)!
*/

import java.util.*;
public class Functions6{
    public static long factorial(long x){
        long f = 1;
        for (long i=1; i<=x; i++){
            f= f*i;
        }
        return f;
    }
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);

        System.out.print(" value of N in nCr: ");
        long n = sc.nextLong();

        System.out.print(" value of R in nCr: ");
        long r = sc.nextLong();
            if (n>=r){
            long diff = n-r;
        
            long nFact = factorial(n); 
            long rFact = factorial(r);
            long diffFact = factorial(diff);

            double nCr = nFact/((rFact)*(diffFact));

            System.out.println("The value of the nCr is: " + (nCr));
 
            }
            else{
                System.out.println("this binomial coeff doesn't exists. ");
            }
  
    }
}