uva 10790 - How Many Points of Intersection?

这题方法很简单，但是要注意数据类型要用longlong,题目中给出了是64bit的

#include<iostream>
using namespace std;
int main(){
    long a,b,temp=1;
    while(cin>>a>>b){
        if(!a&&!b)
            break;
        long long sum=1;
        if(a<2||b<2){
            cout<<"Case "<<temp++<<": 0"<<endl;
            continue;
        }
        sum*=(a-1)*a;
        sum*=(b-1)*b;
        sum/=4;
        cout<<"Case "<<temp++<<": "<<sum<<endl;;
    }
}