#include <bits/stdc++.h>

using namespace std;
#define el '\n'
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define ll long long
#define ld long double
#define ff first
#define ss second
#define lll __int128
const long long N = 5e3 + 1, mod = 1e9 + 7;
const ll inf = 3e18;
double EPS = 1e-14;

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// ● order_of_key (k) : Number of items strictly smaller than k   .
// ● find_by_order(k) : K-th element in a set (counting from zero).
struct line {
    ld x1 , x2 ,  y1 ,  y2  ;
    ld  sx , sy  , slop  , c;
     line (ld x1 ,  ld y1 ,  ld x2 ,  ld y2  ){
        this->x1 =  x1   ;
        this->x2 =  x2  ;
        this->y1=  y1 ;
        this->y2 =  y2  ;
        sx =   (x1-x2) ;
        sy =  (y1-y2) ;
        int g = __gcd((int)sx,(int)sy) ;
        sx/=g ,  sy/=g ;
        slop =  sy/sx ;
        c  =  y1 -  slop*x1 ;
    }
    // for not perpendicular
    // let l_slop  =  sy1/sx1 , sy2/sx2

};
pair<ld , ld >  get_point1  (line l1 , line l2  ){
    // if l1 is perp
    // y  =  mx +c
    ld retx =  l1.x1 ,  rety =  l2.slop*retx +  l2.c ;
    return {retx  ,  rety} ;

}
pair<ld ,ld > get_point2  (line l1 , line l2  ){
    // (sy1/sx1)*x +c = (sy2/sx2)*x +b
    // b-c =  [(sy1/sx1) - (sy2/sx2) ] *x
    // y  =  (slop1 * x  +  c )
    ld retx =  (l1.c-l2.c)/ (l2.slop-l1.slop)  , rety  =  l1.slop * retx +  l1.c  ;
    return {retx, rety} ;
};
ld get_dist (pair<ld ,  ld > p1  ,  pair<ld ,ld >p2){
    return sqrtl((p1.first-p2.first)*(p1.first-p2.first) +(p1.second-p2.second) *(p1.second-p2.second)) ;
}
void acc() {
    vector<line> perp ,  noprep  ;
    int n ;
    cin>>n ;
    for (int i =0 ; i < n ; i++){
        ld x1  ,x2 ,  y1,y2  ;
        cin >>x1>>y1>>x2>>y2 ;
        line l (x1,y1,x2,y2) ;
        if (l.sx==0)perp.push_back(l) ;
        else noprep.push_back(l) ;
    }
    ld ans = 0 ;
    for (int i = 0 ; i  < sz(perp) ; i++){
        for (int j = 0 ; j < sz(noprep) ; j++){
            for (int k = j+1 ; k< sz(noprep) ; k++){
                if (noprep[j].slop == noprep[k].slop)continue  ;
                pair <ld , ld > p1  = get_point1(perp[i] ,  noprep[j]) ;
                pair <ld , ld > p2  = get_point1(perp[i] ,  noprep[k]) ;
                pair <ld , ld > p3  = get_point2(noprep[k] ,  noprep[j]) ;
                ans  =  max (ans  , get_dist(p1,p2) + get_dist(p2,p3) + get_dist(p3,p1)) ;
            }
        }
    }
    for (int i = 0 ; i  < sz(noprep) ; i++){
        for (int j = i+1 ; j < sz(noprep) ; j++){
            for (int k = j+1 ; k< sz(noprep) ; k++){
                if (noprep[j].slop == noprep[k].slop)continue  ;
                if (noprep[i].slop == noprep[k].slop)continue  ;
                if (noprep[i].slop == noprep[j].slop)continue  ;
                pair <ld , ld > p1  = get_point2(noprep[i] ,  noprep[j]) ;
                pair <ld , ld > p2  = get_point2(noprep[i] ,  noprep[k]) ;
                pair <ld , ld > p3  = get_point2(noprep[k] ,  noprep[j]) ;
                ans  =  max (ans  , get_dist(p1,p2) + get_dist(p2,p3) + get_dist(p3,p1)) ;
            }
        }
    }
    if (ans<=0){
        cout <<"no triangle"<<'\n' ;
    }else{
        cout <<setprecision(7)<<fixed<<ans<<'\n' ;
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t = 1;
    //cin >> t;

    while (t--)
        acc();
}
// direction 0 left , 1 right , 2 down , 3 up