#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long
template<typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long double ld;


#define lmao ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5+5 , M = 1e4+5 , MOD = 1e9+7 , LOG = 20 , Msk = 21;

struct Points{
    ld x , y;
};

struct Line{
    Points a , b;
    ld M = 1e-200 , C;
    bool isInfiniteSlope = false;

    void Start(){
        if(b.x == a.x)
            isInfiniteSlope = true;
        else{
            M = (b.y - a.y)/(b.x - a.x);
            C = (b.y - M*b.x);
        }
    }
};
bool isIntersect(Line a , Line b){
    if(a.M == b.M || (a.isInfiniteSlope && b.isInfiniteSlope))
        return false;
    return true;
}

ld getDistance(Points a , Points b){
    return sqrtl((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

Points Get(Line First , Line Second){
    Points ans;
    if(First.isInfiniteSlope){
        ans.x = First.a.x;
        ans.y = (Second.M * ans.x) + Second.C;
    }else if(Second.isInfiniteSlope){

        ans.x = Second.a.x;
        ans.y = (First.M * ans.x) + First.C;
    }else{
        ans.x = (Second.C - First.C)/(First.M - Second.M);
        ans.y = (Second.M * ans.x) + Second.C;
    }
    return ans;
}
void testCase() {
    int n;
    cin >> n;
    vector<Line>v(n);
    for(int i = 0 ; i < n ; i++){
        cin >> v[i].a.x >> v[i].a.y >> v[i].b.x >> v[i].b.y;
        v[i].Start();
    }
    ld ans = -1;
    for(int i = 0 ; i < n ; i++){
        for(int j = i + 1 ; j < n ; j++){
            for(int k = j + 1 ; k < n ; k++){
                if(!isIntersect(v[i],v[j]) || !isIntersect(v[i],v[k]) || !isIntersect(v[j],v[k]))
                    continue;
                Points IJ = Get(v[i],v[j]);
                Points IK = Get(v[i],v[k]);
                Points JK = Get(v[j],v[k]);
                ans = max(ans , getDistance(IJ,IK) + getDistance(IK , JK) + getDistance(IJ , JK));
            }
        }
    }
    if(ans >= 1e-12)
        cout << fixed << setprecision(10) << ans;
    else
        cout << "no triangle";
}

signed main() {

    lmao
    int t = 1;
//    cin >> t;

    while (t--)
        testCase();
}