#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define Elkahraba_mesh_2at3a      \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0);
#define ll long long
//#define double long double
#define int long long
#define ull unsigned long long
#define el "\n"
#define endl "\n"
#define num_of_digits(x) int(log10(x)) + 1
#define ordered_set tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>

const double PI = 3.14159265358979323846;
const ll N = 1e6 + 2, MOD = 1e9 + 7, INF = 1e17, p = 83, p2 = 31;
void fileIO()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
}
// m = (y1 - y2) / (x1 - x2)
// b = y1 - m * x1
// y = mx + b --> in general
// y = m1 * x + b1
// y = m2 * x + b2
// m1 * xi + b1 = m2 * xi + b2
// xi = (b2 - b1) / (m1 - m2)
// yi = m1 * x1 + b1
pair<double, double> inter(double m1, double b1, double m2, double b2)
{
    pair<double, double> ret;
    if (m1 == -1e5)
    {
        return {b1, b1 * m2 + b2};
    }
    if (m2 == -1e5)
    {
        return {b2, b2 * m1 + b1};
    }
    ret.first = (b2 - b1) / (m1 - m2);
    ret.second = m1 * ret.first + b1;
    return ret;
}
pair<double, double> mailbase(double x1, double y1, double x2, double y2)
{
    if (x1 == x2)
        return {-1e5, x1};
    pair<double, double> ret;
    ret.first = (y1 - y2) / (x1 - x2);
    ret.second = y1 - ret.first * x1;
    // cout << ret.first << ' ' << ret.second << el;
    return ret;
}
double dist(pair<double, double> p1, pair<double, double> p2)
{
    return sqrtl((p1.first - p2.first) * (p1.first - p2.first) + (p1.second - p2.second) * (p1.second - p2.second));
}
void Eft7_elkahraba()
{
    int n;
    cin >> n;
    vector<vector<double>> v(n, vector<double>(4));
    for (int i = 0; i < n; i++)
    {
        for (int d = 0; d < 4; d++)
        {
            cin >> v[i][d];
        }
    }
    double ans = 0;
    for (int i = 0; i < n; i++)
    {
        for (int d = i + 1; d < n; d++)
        {
            for (int f = d + 1; f < n; f++)
            {
                // cout << "he : " << i << ' ' << d << ' ' << f << el;
                pair<double, double> mb = mailbase(v[i][0], v[i][1], v[i][2], v[i][3]);
                pair<double, double> mb2 = mailbase(v[d][0], v[d][1], v[d][2], v[d][3]);
                pair<double, double> mb3 = mailbase(v[f][0], v[f][1], v[f][2], v[f][3]);
                if (mb.first == mb2.first or mb.first == mb3.first or mb2.first == mb3.first)
                    continue;
                pair<double, double> inter1 = inter(mb.first, mb.second, mb2.first, mb2.second);
                pair<double, double> inter2 = inter(mb3.first, mb3.second, mb2.first, mb2.second);
                pair<double, double> inter3 = inter(mb.first, mb.second, mb3.first, mb3.second);
                // cout << inter1.first << ' ' << inter1.second << el;
                // cout << inter2.first << ' ' << inter2.second << el;
                // cout << inter3.first << ' ' << inter3.second << el;
                if (inter1 == inter2 and inter1 == inter3)
                {
                    continue;
                }
                ans = max({ans, dist(inter1, inter2) + dist(inter1, inter3) + dist(inter2, inter3)});
            }
        }
    }
    if (ans == 0)
        cout << "no triangle\n";
    else
        cout << fixed << setprecision(10) << ans << el;
}
signed main()
{
    Elkahraba_mesh_2at3a;
    fileIO();
    int _t = 1;
    // cin >> _t;
    while (_t--)
    {
        Eft7_elkahraba();
    }
}