#include <algorithm>
#include <chrono>
#include <cmath>
#include <complex>
#include <iomanip>
#include <iostream>
#include <random>
using ld = double;

int n;
using Point = std::complex<ld>;
Point P[1000007];
int xx[1000007], yy[1000007];
ld diss[1000007][41];
const ld pi = acos(-1);
inline ld dis(Point& lhs, Point& rhs) { return std::abs(lhs - rhs); }
inline ld T(Point& A, Point& B, Point& C) {
  return dis(A, B) + dis(B, C) + dis(C, A);
}

void solve() {
  std::cin >> n;
  std::mt19937 rng(std::chrono::steady_clock::now().time_since_epoch().count());
  ld ans = 1e18;
  for (int i = 1; i <= n; ++i) {
    std::cin >> xx[i] >> yy[i];
  }
  for (int f = 0; f < 4; ++f) {
    Point r =
        std::exp(Point(0, std::uniform_real_distribution<>(-pi, pi)(rng)));
    for (int i = 1; i <= n; ++i) {
      P[i] = Point(xx[i], yy[i]) * r;
    }
    std::sort(P + 1, P + n + 1, [](Point lhs, Point rhs) {
      return (lhs.real() + 1e10) * (lhs.imag() + 1e10) <
             (rhs.real() + 1e10) * (rhs.imag() + 1e10);
    });
    for (int i = 1; i <= n; ++i) {
      for (int j = i + 1; j <= n && j <= i + 27; ++j) {
        diss[i][j - i] = dis(P[i], P[j]);
      }
    }
    for (int i = 1; i <= n - 2; ++i) {
      for (int j = i + 1; j <= n && j <= i + 27; ++j) {
        if (diss[i][j - i] > ans) {
          continue;
        }
        for (int k = j + 1; k <= n && k <= i + 27; ++k) {
          ans = std::min(ans, diss[i][j - i] + diss[j][k - j] + diss[i][k - i]);
        }
      }
    }
  }
  std::cout << std::fixed << std::setprecision(14) << ans << '\n';
}

int main() {
#ifndef ONLINE_JUDGE
  std::freopen("triangle2.in", "r", stdin);
#endif
  std::cin.tie(nullptr)->sync_with_stdio(false);
  int t;
  std::cin >> t;
  for (int i = 1; i <= t; ++i) {
    std::cout << "Case #" << i << ": ";
    solve();
  }
  return 0;
}