HDU-#5053 the Sum of Cube

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;

#define ll __int64
int t,a,b;

ll cube(ll m){
return (m*(m+1)/2)*(m*(m+1)/2);
}

int main(){
int cases=0;
scanf("%d",&t);
while(t--){
scanf("%d%d",&a,&b);
printf("Case #%d: %I64d\n",++cases,cube(b)-cube(a-1));
}
return 0;
}