#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
 
using namespace std;
 
#define EPS 1e-7
#define MAXN 50050
double x[MAXN], w[MAXN];
int n;
 
double Cal(double pos){
    double ans = 0;
    for(int i = 1; i <= n; i ++){
        double tmp = abs(pos - x[i]);
        ans += w[i] * tmp * tmp * tmp;
    }
    return ans;
}
 
double Solve(){
    double Left, Right;
    double mid, midmid;
    double mid_value, midmid_value;
    Left = x[1];
    Right = x[n];
    while(Left + EPS < Right){
        mid = (Left + Right) / 2;
        midmid = (mid + Right) / 2;
        mid_value = Cal(mid);
        midmid_value = Cal(midmid);
        if(mid_value <= midmid_value)
            Right = midmid;
        else
            Left = mid;
    }
    return Cal(Left);
}
 
int main(){
    int t;
    int cnt = 0;
    scanf("%d", &t);
    while(t --){
        cnt ++;
        scanf("%d", &n);
        for(int i = 1; i <= n; i ++){
            scanf("%lf %lf", &x[i], &w[i]);
        }
        printf("Case #%d: %.0lf\n", cnt, Solve());
    }
    return 0;
}