#include<bits/stdc++.h>
using namespace std;
#ifndef BADGNU
#pragma GCC target("sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#endif
#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ll long long
#define int ll
#define ld long double
#define y1 cheza
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T> using ordered_multiset = tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
const int N=2100;
const int M=5001;
const int B=447;
const int mod=998244353;
const ll INF=1e18;
const int dx[]={1,-1,0,0};
const int dy[]={0,0,1,-1};
const double eps=1e-6;
int n;
int a[N];
int pref[N];
// pair<int,int> dp[N][N];
bool operator<(const pair<int,int>&x,const pair<int,int>&y){
return x.first*y.second<y.first*x.second;
}
bool operator<=(const pair<int,int>&x,const pair<int,int>&y){
return x.first*y.second<=y.first*x.second;
}
bool operator>(const pair<int,int>&x,const pair<int,int>&y){
return x.first*y.second>y.first*x.second;
}
bool operator>=(const pair<int,int>&x,const pair<int,int>&y){
return x.first*y.second>=y.first*x.second;
}
bool operator==(const pair<int,int>&x,const pair<int,int>&y){
return x.first*y.second==y.first*x.second;
}
pair<int,int>max(const pair<int,int>&x,const pair<int,int>&y){
if(x<y){
return y;
}
return x;
}
pair<int,int>min(const pair<int,int>&x,const pair<int,int>&y){
if(x>y){
return y;
}
return x;
}
pair<int,int>ans={1e9,1};
map<tuple<int,int,pair<int,int>,pair<int,int>>,bool>dp;
void dfs(int l,int r,pair<int,int>mx,pair<int,int>mn){
mx=max(mx,make_pair(pref[r]-pref[l-1],(r-l+1)));
mn=min(mn,make_pair(pref[r]-pref[l-1],(r-l+1)));
if(dp.count({l,r,mx,mn}))return;
dp[{l,r,mx,mn}]=1;
if(l==r){
pair<int,int>res={(mx.first*mn.second-mn.first*mx.second),(mx.second*mn.second)};
ans=min(ans,res);
return;
}
dfs(l+1,r,mx,mn);
dfs(l,r-1,mx,mn);
}
void test(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
pref[i]=pref[i-1]+a[i];
}
dfs(1,n,{pref[n],n},{pref[n],n});
ld res=ans.first/((ld)ans.second);
cout<<fixed;
cout<<setprecision(10);
cout<<res<<'\n';
}
/*
*/
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// cout.tie(nullptr);
int t2=1;
// cin>>t2;
for(int i=1;i<=t2;i++){
test();
}
}
