import java.util.Scanner;

/**
 * Created by buddhimah on 10/16/2017.
 */
public class NCR {
    public static  int fac(int num){

        int r;

        if(num==1){
            return 1;

        }
        r= fac(num-1)*num;

        return r;


    }

    public static void main(String args[]){

        Scanner sc = new Scanner(System.in);
        System.out.println("Enter n ");

        int n =sc.nextInt();
        System.out.println("Enter k: ");

        int k =sc.nextInt();

        System.out.println(fac(n)/(fac(n-k)*fac(k)));


    }
}