> #include<stdio.h>
> int main()
> {
> 	int n,m,i;
> 	while(scanf("%d%d",&n,&m) && (n || m))
> 	{
> 		double c=1.0;
> 		for(i=n;i>n-m;i--) c*=i;
> 		for(i=m;i>1;i--) c/=i;
> 		printf("%d things taken %d at a time is %.0lf exactly.\n",n,m,c);
> 	}
> 	return 0;
> }