HDU 4355

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#define LL __int64
using namespace std;
const int N=50050;

double point[N];
double weight[N];
int n;

double cal(double x){
	double ans=0,t;
	for(int i=1;i<=n;i++){
		t=fabs(x-point[i]);
		ans+=(t*t*t*weight[i]);
	}
	return ans;
}

int main(){
	int T,t=0;
	scanf("%d",&T);
	while(++t<=T){
		scanf("%d",&n);
		for(int i=1;i<=n;i++)
		scanf("%lf%lf",&point[i],&weight[i]);
		double l=point[1],r=point[n],m,mm;
		while(l+(1e-8)<=r){
			m=l+(r-l)/3;
			mm=r-(r-l)/3;
			if(cal(m)>cal(mm))
			l=m;
			else r=mm;
		}
		double ans=cal(l);
		printf("Case #%d: %.0lf\n",t,ans);
	}
	return 0;
}