#include<stdio.h>

longlong sum;

int main()

{

int k,n,m;

while(~scanf("%d%d",&n,&m)&&(n!=0||m!=0))

{

sum =1;

m = m<(n-m)?m:n-m;

for(k =1;k <= m;k++)

sum =(sum*(n-m+k))/k;

printf("%lld\n",sum);

}

return0;}