#include<bits/stdc++.h>
using namespace std;
#define LL long long int
#define rep(i,m) for(i=0;i<m;i++)
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
vector<double> myvec;
void push(double a1,double b1,double a2,double b2){
double temp=(double)sqrt((a1-a2)*(a1-a2)+(b1-b2)*(b1-b2));
myvec.push_back(temp);
if(myvec.size()>3){sort(myvec.begin(),myvec.end());myvec.erase(myvec.begin()+3);}
}
int main()
{_
LL i,j,k,n,t,d,p;
string s1,s2;
cin>>t;j=0;
while(j<t){j++;
cin>>n;double a[n],b[n];myvec.clear();
for(i=0;i<n;i++)cin>>a[i]>>b[i];
for(i=0;i<n;i++)
for(j=i+1;j<n;j++)
push(a[i],b[i],a[i+1],b[i+1]);
cout<<"Case "<<j<<": "<<std::setprecision(10)<<myvec[0]+myvec[1]+myvec[0]<<endl;
}
return 0;
}
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