#include <bits/stdc++.h>
// iostream is too mainstream
#include <cstdio>
// bitch please
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <cmath>
#include <iomanip>
#include <time.h>
#define dibs reserve
#define OVER9000 1234567890
#define ALL_THE(CAKE,LIE) for(auto LIE =CAKE.begin(); LIE != CAKE.end(); LIE++)
#define tisic 47
#define soclose 1e-8
#define chocolate win
// so much chocolate
#define patkan 9
#define ff first
#define ss second
#define abs(x) ((x < 0)?-(x):x)
#define uint unsigned int
#define dbl long double
#define pi 3.14159265358979323846
using namespace std;
// mylittledoge

#ifdef DONLINE_JUDGE
	// palindromic tree is better than splay tree!
	#define lld I64d
#endif

int main() {
	freopen("angry.in","r",stdin);
	freopen("angry.out","w",stdout);
	cin.sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(10);
	int N;
	cin >> N;
	vector<long long> X(N);
	for(int i =0; i < N; i++) cin >> X[i];
	sort(begin(X),end(X));
	N =unique(begin(X),end(X))-begin(X);
	X.resize(N);
	for(int i =0; i < N; i++) X[i] *=2;
	map<long long,int> Xs;
	for(int i =0; i < N; i++) Xs[X[i]] =i;

	vector<long long> minRl(N,OVER9000), minRr(N,OVER9000);
	minRl[0] =-2;
	for(int i =1; i < N; i++) {
		long long Ra =-1, Rb =OVER9000;
		while(Rb-Ra > 1) {
			long long R =(Ra+Rb)/2;
			auto it =Xs.lower_bound(X[i]-R);
			if(it->ss == i) {Ra =R; continue;}
			if(minRl[it->ss] > R-2) Ra =R;
			else Rb =R;}
		minRl[i] =Rb;}
	minRr[N-1] =-2;
	for(int i =N-2; i >= 0; i--) {
		long long Ra =-1, Rb =OVER9000;
		while(Rb-Ra > 1) {
			long long R =(Ra+Rb)/2;
			auto it =Xs.upper_bound(X[i]+R);
			it--;
			if(it->ss == i) {Ra =R; continue;}
			if(minRr[it->ss] > R-2) Ra =R;
			else Rb =R;}
		minRr[i] =Rb;}

	long long Ra =-1, Rb =OVER9000;
	while(Rb-Ra > 1) {
		long long R =(Ra+Rb)/2;
		bool ok =false;
		for(int i =0; i < N; i++) {
			auto it =Xs.upper_bound(X[i]+2*R);
			it--;
			if(max(minRl[i],minRr[it->ss])+2 <= R) ok =true;}
		if(ok) Rb =R;
		else Ra =R;}

	cout << Rb/2 << ((Rb%2 == 0)?".0":".5") << "\n";
	return 0;}

// look at my code
// my code is amazing