#include <bits/stdc++.h>
using namespace std;
constexpr int MAXN = 1000005;
int n, T; pair<double, double> A[MAXN]; vector<int> To[MAXN];
double Ans = INFINITY, Lim = INFINITY;
double dis(int i, int j){return hypot(A[i].first - A[j].first, A[i].second - A[j].second);}
int main(){
  cin.tie(nullptr)->sync_with_stdio(false);
  cin >> T; for(int t = 1; t <= T; t++){
    cin >> n; double alpha = (double)mt19937(time(nullptr))() / UINT32_MAX * acos(-1);
    Ans = Lim = INFINITY;
    for(int i = 1; i <= n; i++){
      int x, y; cin >> x >> y, alpha = 0;
      A[i].first  = x * cos(alpha) - y * sin(alpha);
      A[i].second = y * cos(alpha) + x * sin(alpha);
      To[i].clear();
    }
    sort(A + 1, A + n + 1);
    for(int i = 1; i <= n; i++){
      double mn = INFINITY, se = INFINITY;
      for(int j = -50; j <= 50; j++) if(j && 1 <= i + j && i + j <= n){
        double len = dis(i, i + j);
        if(len < mn) se = mn, mn = len; else se = min(se, len);
      }
      Lim = min(Lim, mn + se);
    }
    for(int i = 1; i <= n; i++)
      for(int j = 1; j <= 50 && i + j <= n; j++) if(dis(i, i + j) < Lim * 1.1 + 0.1)
        To[i].push_back(i + j), To[i + j].push_back(i);
    for(int i = 1; i <= n; i++) for(auto j: To[i]) for(auto k: To[j]) for(auto t: To[k])
      if(t == i){Ans = min(Ans, dis(i, j) + dis(j, k) + dis(k, i)); break;}
    cout << "Case #" << t << ": " << fixed << setprecision(14) << Ans << '\n';
  }
  cerr << (double)clock() / CLOCKS_PER_SEC << endl;
  return 0;
}