uva10790 How Many Points of Intersection?

uva的题目真是奇怪，另外在查找排序的那个里面我还有一道题目，始终读不懂题意，郁闷.....

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