#include<bits/stdc++.h>
using namespace std;
double ax,bx,cx,dx,ay,by,cy,dy;

double dis(double mid)
{
     double x1=ax+(bx-ax)*mid;
     double y1=ay+(by-ay)*mid;
     double x2=cx+(dx-cx)*mid;
     double y2=cy+(dy-cy)*mid;

    double d=sqrt(((x2-x1)*(x2-x1))+((y2-y1)*(y2-y1)));
    return d;
}

int main()
{
    int t,i,j;
    double hi,lo,mid1,mid2;
    cin>>t;
    for(i=1;i<=t;i++)
    {
        cin>>ax>>ay>>bx>>by>>cx>>cy>>dx>>dy;
        hi=1.0,lo=0.0;
        for(j=1;j<=43;j++)
        {
            mid1=(lo*2.0+hi)/3.0;
            mid2=(lo+hi*2.0)/3.0;
            if(dis(mid1)>dis(mid2))
                lo=mid1;
            else
                hi=mid2;
        }
        double ans= dis((lo+hi)/2.0);
         printf("Case %d: %.10lf\n",i,ans);
    }
    return 0;
}