/// Md.ASADUZZAMAN
/// Dept of ICT
/// MBSTU
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define fr(i,a,b) for(int i=(a);i<(b);i++)
#define rfr(i,a,b) for(int i=(b-1);i>=(a);i--)
#define freach(i, c) for( __typeof( (c).begin() ) i = (c).begin(); i != (c).end(); ++i )
#define rep(i,n) for(int i=0;i<(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define forit(it, s) for(__typeof(s.begin()) it = s.begin(); it != s.end(); it++)
#define PINF INT_MAX
#define MINF INT_MIN
#define pb push_back
#define mp make_pair
#define all(a) (a).begin(),(a).end()
#define mset(a,c) memset(a,c,sizeof a)
#define clr(a) memset(a,0,sizeof a)
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pcc pair<char,char>
#define pic pair<int,char>
#define pci pair<char,int>
#define psi pair<sting,int>
#define pis pair<int,string>
#define ff first
#define ss second
#define vs vector<string>
#define vi vector<int>
#define vll vector<long long>
#define vpi vector<pair<int,int> >
#define vpl vector<pair<long long,long long> >
#define vpcl vector<pair<c,long long> >
#define vpsl vector<pair<string,long long> >
#define qi queue<int>
#define ql queue<long>
#define qll queue<long long>
#define PQ priority_queue
#define mpii map<int,int>
#define mpsl map<string,long long>
#define mpcl map<char,long long>
#define mpll map<long long,long long>
#define stl set<ll>
#define sts set<string>
/// Bug
#define bug(x) cout<<#x<<": "<<x<<endl
#define bug1(x,y) cout<<#x<<": "<<x<<" | "<<#y<<": "<<y<<endl
#define bug2(x,y,z) cout<<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl
#define bug3(w,x,y,z) cout<<#w<<": "<<w<<" | "<<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl
/// Trigonometry
#define pi acos(-1.0)
#define rad(x) (((1.0 * x * pi) / 180.0))
#define deg(x) (((x * 180.0) / (1.0 * pi)))
#define sinr(x) (sin(rad(x)))
#define cosr(x) (cos(rad(x)))
#define tanr(x) (tan(rad(x)))
#define asind(x) (deg((asin(x))))
#define acosd(x) (deg((acos(x))))
#define atand(x) (deg((atan(x))))
///Bit
#define setbiton(x, i) (x |= (1 << i))
#define setbitoff(x, i) (x &= (~(1 << i)))
#define togglebit(x, i) (x ^= (1 << i))
#define checkbiton(x,i) ((x &(1 << i))!=0)
#define ispow2 (x!=0 && (x&(x-1))==0)
#define countbit(x) __builtin_popcountll((ll)x)
#define countlead(x) __builtin_clzll((ll)x) ///give wrong ans for zero (0)
#define counttrail(x) __builtin_ctzll((ll)x) ///give wrong ans for zero (0)
/// Search
#define LB(a,x) (lower_bound(all(a),x)-a.begin()) // first element in the range [first,last) which does not compare less than val.
#define UB(a,x) (upper_bound(all(a),x)-a.begin()) // first element in the range [first,last) which compares greater than val.
#define bin_sa(a,n,x) (binary_search(a, a+n,x))
#define bin_sv(v,x) (binary_search(v.begin(), v.end(),x))
/// Algorithm
#define Unique(store) store.resize(unique(store.begin(),store.end())-store.begin())
#define mxe(a,n) (*max_element(a,a+n))
#define mxv(v) (*max_element(v.begin(), v.end()))
#define mne(a,n) (*min_element(a,a+n))
#define mnv(v) (*min_element(v.begin(), v.end()))
#define SUM(a,n) (accumulate(a,a+n,0))
#define SUMv(v) (accumulate(v.begin(), v.end(), 0))
#define occurx(v,x) (count(v.begin(), v.end(),x))
#define findx(v,x) (find(v.begin(), v.end(),x))
#define swap(a,b) a^=b^=a^=b
#define sgn(x,y) ((x)+eps<(y)?-1:((x)>eps+(y)?1:0))
///I/O
#define input() freopen("in0.txt","r",stdin)
#define output()freopen("out0.txt","w",stdout)
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define ppc(x,y) cout<<fixed<<setprecision(y)<<x<<endl
#define IN scanf
#define OUT printf
/// #define SI(a) scanf("%d",&a)
/// #define SL(a) scanf("%lld",&a)
/// #define SD(a) scanf("%lf",&a)
/// #define OI(a) printf("%d",a)
/// #define OL(a) printf("%lld",a)
/// #define OD(a) printf("%lf",a)
/// #define ON() printf("\n")
#define EPS 1e-9
#define inf 1e18
#define MOD 1000000007
template<typename T>inline string toString(T a){ ostringstream os("");os<<a;return os.str();}
template<typename T>inline ll toLong(T a){ll res;istringstream os(a);os>>res;return res;}
///----------------------Main Code-------------------------------------///
double fun(double m,vpl v,vpl v1)
{
double x1=v[0].ff+(v[1].ff-v[0].ff)*m*1.0;
double y1=v[0].ss+(v[1].ss-v[0].ss)*m*1.0;
double x2=v1[0].ff+(v1[1].ff-v1[0].ff)*m*1.0;
double y2=v1[0].ss+(v1[1].ss-v1[0].ss)*m*1.0;
return (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
}
int main()
{
#ifndef ONLINE_JUDGE
input();
output();
#endif
fast();
// clock_t begin, end;
// double time_spent;
// begin = clock();
ll n, x, y, a, b, c=1, t, q;
string s;
//char c;
cin>>t;
while (t--)
{
vpl v,v1;
fr(i,0,2)
cin>>x>>y,v.pb(mp(x,y));
fr(i,0,2)
cin>>x>>y,v1.pb(mp(x,y));
ll k=200;
double s=0.0,e=1.0;
while(k--)
{
double l1=(2*s+e)/3.0;
double l2=(2*e+s)/3.0;
if(fun(l1,v,v1)<fun(l2,v,v1))
e=l2;
else s=l1;
}
//bug(n);
double r=(double)sqrt(fun(e,v,v1));
q=r;
if(r!=q)
cout<<"Case "<<c++<<": "<<fixed<<setprecision(10)<<sqrt(fun(e,v,v1))<<endl;
else cout<<"Case "<<c++<<": "<<q<<endl;
}
// end = clock();
// time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
// cout<<"Time spent = "<<time_spent<<endl;
return 0;
}