#include <bits/stdc++.h>

using i64 = long long;

struct Point {
    int x = 0;
    int y = 0;
};

Point operator-(const Point &a, const Point &b) {
    return {a.x - b.x, a.y - b.y};
}

int cross(const Point &a, const Point &b) {
    return a.x * b.y - a.y * b.x;
}

int dot(const Point &a, const Point &b) {
    return a.x * b.x + a.y * b.y;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n;
    std::cin >> n;
    
    std::vector<std::array<Point, 3>> a(n);
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < 3; j++) {
            std::cin >> a[i][j].x >> a[i][j].y;
        }
    }
    
    std::vector<double> f(1 << n);
    for (int s = 1; s < (1 << n); s++) {
        std::vector<Point> ps;
        for (int i = 0; i < n; i++) {
            if (s >> i & 1) {
                for (int j = 0; j < 3; j++) {
                    ps.push_back(a[i][j]);
                }
            }
        }
        std::sort(ps.begin(), ps.end(),
            [&](const Point &a, const Point &b) {
                return a.x < b.x || (a.x == b.x && a.y < b.y);
            });
        std::vector<Point> h, l;
        for (auto p : ps) {
            while (h.size() > 1 && cross(h.back() - h[h.size() - 2], p - h.back()) >= 0) {
                h.pop_back();
            }
            h.push_back(p);
            while (l.size() > 1 && cross(l.back() - l[l.size() - 2], p - l.back()) <= 0) {
                l.pop_back();
            }
            l.push_back(p);
        }
        for (int i = 1; i < h.size(); i++) {
            f[s] += std::sqrt(dot(h[i - 1] - h[i], h[i - 1] - h[i]));
        }
        for (int i = 1; i < l.size(); i++) {
            f[s] += std::sqrt(dot(l[i - 1] - l[i], l[i - 1] - l[i]));
        }
    }
    std::vector<double> dp(1 << n, 1E9);
    dp[0] = 0;
    for (int s = 1; s < (1 << n); s++) {
        int u = __builtin_ctz(s);
        int ns = s ^ (1 << u);
        for (int t = ns; ; t = (t - 1) & ns) {
            dp[s] = std::min(dp[s], dp[t] + f[s ^ t]);
            if (!t) {
                break;
            }
        }
    }
    std::cout << std::fixed << std::setprecision(10);
    std::cout << dp.back() << "\n";
    
    return 0;
}