#include<iostream>
#include<vector>
#include<set>
#include<algorithm>
#include<deque>
#include<map>
#include<cmath>
#include<iomanip>

using namespace std;

#define int long long

vector<double> vec;
vector<double> lft;
vector<double> rght;
int n;

bool f(double r) {
	for (int i = 0; i < n; i++) {
		double d1 = vec[i] + r + r;
		auto it = upper_bound(vec.begin(), vec.end(), d1);
		it--;
		int t = it - vec.begin();
		if(lft[i] + 1 <= r && rght[t] + 1 <= r) {
			return 1;
		}
		d1 -= r * 4;
		it = lower_bound(vec.begin(), vec.end(), d1);
		t = it - vec.begin();
		if (rght[i] + 1 <= r && lft[t] + 1 <= r) {
			return 1;
		}
	}
	return 0;
}

signed main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	vec.resize(n);
	for (int i = 0; i < n; i++) {
		cin >> vec[i];
	}
	sort(vec.begin(), vec.end());
	lft.resize(n);
	rght.resize(n);
	for (int i = 1; i < n; i++) {
		lft[i] = max(lft[i - 1] + 1, abs(vec[i] - vec[i - 1]));
	}
	for (int i = n - 2; i >= 0; i--) {
		rght[i] = max(abs(vec[i] - vec[i + 1]), rght[i + 1] + 1);
	}
	double l = 0;
	double r = 1e9;
	for(int i = 0; i < 50; ++i) {
		double m = (l + r) / 2.0;
		if (f(m)) {
			r = m;
		}
		else {
			l = m;
		}
	}
	cout << fixed << setprecision(1) << r;
}