#include<bits/stdc++.h>
using namespace std;
#define N 50500
struct node{
    double p;
    double w;
}a[N];
int n;
double sum(double mid){
    double sum=0.0;
    for(int i=0;i<n;i++){
        double s=fabs(a[i].p-mid);
        sum+=s*s*s*a[i].w;
    }
    return sum;
}
double sanfen(double l,double r){
    double mid,midd,ans1,ans2,left,right;
    left=l;right=r;
    while(left+0.000000001<right){
        mid=(left+right)/2.0;
        midd=(mid+right)/2.0;
        ans1=sum(mid);
        ans2=sum(midd);
        if(ans1<ans2)right=midd;
        else left=mid;
    }
    return left;
}
int main(){
    int t,num;
    double left,right,ans,m;
    num=0;
    while(~scanf("%d",&t)){
      while(t--){
            num++;
            left=1e5;right=1e-5;
            scanf("%d",&n);
        for(int i=0;i<n;i++){
            scanf("%lf%lf",&a[i].p,&a[i].w);
            left=min(left,a[i].p);
            right=max(right,a[i].p);
        }
        m=sanfen(left,right);
        ans=sum(m);
        printf("Case #%d: %.0lf\n",num,ans);
     }
    }
     return 0;
}