#include <stdio.h>

int main()
{
	__int64 result, a, b, i, mod;
	while( scanf("%I64d%I64d", &a, &b) != -1 )
	{
		if(a == 0 && b == 0)
		{
			break;	
		}
		
		if(a < 2 * b)
		{
			b = a - b;	
		}
		
		for(i=1,result=1;i<=b;i++)
		{
			result*=(a-b)+i;
			result/=i;	
		}
		

		printf("%I64d\n",result);	
	}
	return 0;
}