#pragma GCC optimize("O3")
#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back
#define sz(x) ((int)x.size ())
#define all(x) (x).begin(), (x).end()
#define re return
#define mp make_pair
#define sqrt(x) sqrt (abs(x))
#define y0 y3451
#define y1 y4562
#define makeunique(x) sort(all(x)), (x).resize (unique(all(x)) - (x).begin())
#define endl '\n'

typedef pair <int, int> ii;
typedef long long ll;
typedef unsigned long long ull;
typedef double D;
typedef long double ld;
typedef unsigned int uint;
typedef vector <string> vs;
typedef vector <int> vi;
typedef vector <ii> vii;
typedef vector <ll> vll;
typedef vector <vi> vvi;

template <class T> T abs (T x) { re x > 0 ? x : -x; }
template <class T> T sqr (T x) { re x * x; }
template <class T> T gcd (T a, T b) { re a ? gcd (b % a, a) : b; }
template <class T> int sgn (T x) { re x > 0 ? 1 : (x < 0 ? -1 : 0); }

#define filename ""

const D pi = acos(-1.);
const int N = 3e5 + 20;
const int inf = 1e9 + 7;

int n, m;
double eps = 1e-8;

struct seg {
	double x0, y0, x1, y1;
	double get (double x) {
		return (x - x0) * (y1 - y0) / (x1 - x0) + y0;
	}
} a[N];

struct node {
	int id;
	ll pr;
	node* left, * right;
	node (int i) {
		left = right = 0;
		pr = rand() + (rand() << 15);
		id = i;
	}
};

double dist (double x, double y, int i) {

	return 0;
}

bool intersect (int i, int j, double X) {
   	double ans = inf;
   	ans = min (ans, dist(a[i].x0, a[i].y0, j));
   	ans = min (ans, dist(a[i].x1, a[i].y1, j));
   	ans = min (ans, dist(a[j].x0, a[j].y0, i));
   	ans = min (ans, dist(a[j].x0, a[j].y0, i));
	return ans < X * X;
}

void merg (node* l, node* r, node*& t) {
	if (!l || !r) { t = l ? l : r; re; }
	if (l->pr > r->pr) {
		merg (l->right, r, l->right), t = l;
	} else {
		merg (l, r->left, r->left), t = r;
	}
}

void split (node* t, node*& l, node*& r, double key, double x) {
	if (!t) re;
	auto k = a[t->id].get(x);
	if (k > key + eps) {
	 	split (t->left, l, t->left, key, x), r = t;
	} else {
	 	split (t->right, t->right, r, key, x), l = t;
	}
}

node* getr (node* root) {
	while (root->right) root = root->right;
	re root;
}

node* getl (node* root) {
	while (root->left) root = root->left;
	re root;
}

bool check (double X) {
	vector<pair<pair<double, int>, int>> ev;
	for (int i = 0; i < n; i++) {
		if (abs(a[i].x0 - a[i].x1) < eps) ev.pb(mp(mp(a[i].x0 - X * 0.5, 1), i));
		else {
		    double x0 = a[i].x0 - X * 0.5;
		    double x1 = a[i].x1 + X * 0.5;
		 	ev.pb(mp(mp(x0, 0), i));
		 	ev.pb(mp(mp(x1, 2), i));
		}
	}
	sort(all(ev));
	ok = false;
	for (auto x : ev) {
//
	}
	re ok;
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	cin >> n;
	for (int i = 0; i < n; i++) cin >> a[i].x0 >> a[i].y0 >> a[i].x1 >> a[i].y1;
	double l = 0;
	double r = inf;
	for (int i = 0; i < 60; i++) {
		double c = (l + r) * 0.5;
		if (check(c)) r = c;
		else l = c;
	}
}