#include <bits/stdc++.h>
using namespace std;
constexpr int MAXN = 1000005;
int n, T; pair<double, double> A[MAXN];
struct cmp{
  bool operator () (const pair<double, double> &l, const pair<double, double> &r) const {
    return l.second < r.second || (l.second == r.second && l.first < r.first);
  }
};
double dis(const pair<double, double> &l, const pair<double, double> &r){
  return hypot(l.first - r.first, l.second - r.second);
}
int main(){
  cin.tie(nullptr)->sync_with_stdio(false);
  cin >> T; for(int t = 1; t <= T; t++){
    cin >> n; double Ans = INFINITY;
    multiset<pair<double, double>, cmp> S;
    for(int i = 1; i <= n; i++) cin >> A[i].first >> A[i].second;
    sort(A + 1, A + n + 1);
    for(int i = 1, j = 1; i <= n; i++){
      while(j < i && A[i].first - A[j].first > Ans) S.erase(S.find(A[j++]));
      auto l = S.lower_bound(make_pair(-INFINITY, A[i].second - Ans));
      auto r = S.upper_bound(make_pair( INFINITY, A[i].second + Ans));
      for(auto x = l; x != r; x++) for(auto y = l; y != x; y++)
        Ans = min(Ans, dis(A[i], *x) + dis(*x, *y) + dis(*y, A[i]));
      S.insert(A[i]);
    }
    cout << "Case #" << t << ": " << fixed << setprecision(14) << Ans << '\n';
  }
  cerr << (double)clock() / CLOCKS_PER_SEC << endl;
  return 0;
}