import java.util.Scanner;

public class Spock
{

    public static int C(int n, int k)
    // Preconditions:  0 <= k <= n
    // Postcondition:  return n-choose-k, the number of subsets of size k of 
    //  a set of n planets
    {
       // only one way not to choose any of them;
       // only one way to choose all of them ...
       if (k == 0 || k == n) return 1;

       else return C(n-1,k-1)  // choose Planet X and count ways of choosing
                               //   remaining k-1 from remaining n-1 planets
                 + C(n-1,k);   // don't choose Planet X and count ways of
                               //   choosing k from remaining n-1 planets
    }

    public static void main(String[] args)
    {
        Scanner Input = new Scanner(System.in);
        System.out.print("Enter number of planets to choose from: ");
        int n = Input.nextInt();
        System.out.print("Enter number he can visit: ");
        int k = Input.nextInt();
        System.out.println("\n\nThere are " + C(n,k) + " ways to choose " + k 
                           + " of the planets\n");
    }
}