7058

#include<bits/stdc++.h>

using namespace std;

///Template
#define in1()    freopen("C:\\Users\\SHESHER\\Rest\\Desktop\\MY COMPUTER\\Code\\Template\\CB\\input.txt", "r", stdin);
#define out1()   freopen("C:\\Users\\SHESHER\\Rest\\Desktop\\MY COMPUTER\\Code\\Template\\CB\\output.txt", "w", stdout);


//Data types
#define l       long
#define ll      long long
#define llu     unsigned long long

//loop
#define f1(i,x,y)   for(int i=x;i<=y;i++)

//Constants
#define MAX     10000007
#define PI      acos(-1.0)

struct rcrd
{
    int t, x;
};

bool cmp(struct rcrd i, struct rcrd j)
{
    return i.t<j.t;
}

int main()
{
//    in1();
    int ts;
    cin>>ts;
    for(int ti=1;ti<=ts;ti++){
        int n;
        cin>>n;
        struct rcrd a[111111];
        for(int i=0;i<n;i++){
            cin>>a[i].t>>a[i].x;
        }

        sort(a, a+n, cmp);

//        for(int i=0;i<n;i++){
//            cout<<a[i].t<<" "<<a[i].x<<endl;
//        }
        int di, t2;
        double mx=0;
        for(int i=0;i<n-1;i++){
            di=abs(a[i].x-a[i+1].x);
            t2=abs(a[i+1].t-a[i].t);
            double sp=di/(t2*1.0);
            if(sp>=mx) mx=sp;
        }
//        cout<<mx<<endl;

        int mx1=mx*1000;
        double mx2=mx1/10;
        int xm=mx1%10;
        if(xm>=5) mx2++;
        double ans=mx2/100.0;
        printf("Case #%d: %.2lf\n", ti, ans);
    }
    return 0;
}