UVA 10790 多少个交点

http://www.cnblogs.com/xiaocai905767378/archive/2011/04/27/2030213.html

#include<stdio.h>int main(){ long long a,b; int n=1; while(scanf("%lld%lld",&a,&b)!=EOF&&(a||b)) printf("Case %d: %lld\n",n++,b*(b-1)*a*(a-1)/4); return 0;}