#include<bits/stdc++.h>
#define LL long long
#define LLL __int128
#define uint unsigned
#define ldb long double
#define uLL unsigned long long
using namespace std;
const int N=1e6+5;
const ldb INF=1e10;
int n;ldb ans;pair<int,int>A[N];
inline ldb dist(const int&x,const int&y){
    const auto [xx,xy]=A[x];const auto [yx,yy]=A[y];
    return sqrtl(1.l*(xx-yx)*(xx-yx)+1.l*(xy-yy)*(xy-yy));
}
inline void solve(int l,int r){
    if(r-l<2)return;
    const int mid=(l+r)>>1;
    solve(l,mid),solve(mid+1,r);
    const int lx=max_element(A+l,A+mid+1)->first;
    const int rx=min_element(A+mid+1,A+r+1)->first;
    set<int>S;
    for(int i=l,lp=mid+1,rp=mid+1;i<=mid;++i)
        if((rx-A[i].first)*2.<ans){
            for(;rp<=r&&(A[rp].second-A[i].second)*2.<ans;++rp)
                if((A[rp].first-lx)*2.<ans)S.emplace(rp);
            for(;lp<rp&&(A[i].second-A[lp].second)*2.>=ans;++lp)S.erase(lp);
            set<int>T;
            for(auto j:S)if(fabs(A[j].first-lx)*2.<ans)T.emplace(j);
            S=T;
            for(auto j:S)for(auto k:S)
                if(k<j)ans=min(ans,dist(i,j)+dist(j,k)+dist(i,k));
                else break;
        }
    S.clear();
    for(int i=mid+1,lp=l,rp=l;i<=r;++i)
        if((A[i].first-lx)*2.<ans){
            for(;rp<=mid&&(A[rp].second-A[i].second)*2.<ans;++rp)
                if((rx-A[rp].first)*2.<ans)S.emplace(rp);
            for(;lp<rp&&(A[i].second-A[lp].second)*2.>=ans;++lp)S.erase(lp);
            set<int>T;
            for(auto j:S)if(fabs(rx-A[j].first)*2.<ans)T.emplace(j);
            S=T;
            for(auto j:S)for(auto k:S)
                if(k<j)ans=min(ans,dist(i,j)+dist(j,k)+dist(i,k));
                else break;
        }
    inplace_merge(A+l,A+mid+1,A+r+1,
    [&](const pair<int,int>&x,const pair<int,int>&y){
        return x.second<y.second;
    });
}
inline void MAIN(){
    cin>>n,ans=INF;
    for(int i=1;i<=n;++i)
        cin>>A[i].first>>A[i].second;
    sort(A+1,A+n+1),solve(1,n);
    cout<<fixed<<setprecision(12)<<ans<<'\n';
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    int t=1;cin>>t;for(int _=1;t--;++_)
        cout<<"Case #"<<_<<": ",MAIN();
    return 0;
}