C++ :

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, k;
	while (scanf("%d%d", &n, &k) == 2) {
		if (n == 0 && k == 0) break;
		
		if (k < n - k) k = n - k;
		
		long long res = 1;
		for (int i = 1; i <= n - k; i ++) {
			res = res * (k + i) / i;
		}
		printf("%d\n", res);
	}	

	return 0;
}