UVA10790上下俩条线段上的点最多形成线段交点

很简单的规律，竟然想了半天，智商显然低，

#include<cstdio>#include<iostream>#include<vector>#include<queue>#include<algorithm>#include<string>#include<cstdlib>#include<map>#include<set>#include<cmath>#include<cstring>#include<cctype>#include<climits>#include<memory>#include<climits>#include<cstdlib>using namespace std;#define LL long long#define INT (1<<31)-1;int main(){    LL a,b;    int cas=0;    while(scanf("%lld%lld",&a,&b)!=EOF)    {        if(!a&&!b) break;        printf("Case %d: %lld\n",++cas,a*(a-1)*b*(b-1)/4);    }    return 0;}