import java.util.Scanner;
import java.io.BufferedInputStream;

public class Main {

    public static void main(String[] args) {
    		
        Scanner in = new Scanner(new BufferedInputStream(System.in));
        long n = in.nextLong(), k = in.nextLong();

        while(n > 0){
        	long kCn = 1;
        	k = (k > n-k ? n-k : k);
        	for(long i = n, j = 1; j <= k; i--, j++)
        		kCn = kCn * i / j;

        	System.out.println(kCn);

        	n = in.nextLong(); k = in.nextLong();
        }

        in.close();
    }

}