#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=2e5+100;
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];
struct ki{
int first,second;
};
bool operator<(const ki&x,const ki&y){
return x.first*y.second<y.first*x.second;
}
bool operator<=(const ki&x,const ki&y){
return x.first*y.second<=y.first*x.second;
}
bool operator>(const ki&x,const ki&y){
return x.first*y.second>y.first*x.second;
}
bool operator>=(const ki&x,const ki&y){
return x.first*y.second>=y.first*x.second;
}
bool operator==(const ki&x,const ki&y){
return x.first*y.second==y.first*x.second;
}
ki operator-(const ki&x,const ki&y){
ki res={(x.first*y.second-y.first*x.second),(x.second*y.second)};
// int g=gcd(res.first,res.second);
// res.first/=g;
// res.second/=g;
return res;
}
ki max(const ki&x,const ki&y){
if(x<y){
return y;
}
return x;
}
ki min(const ki&x,const ki&y){
if(x>y){
return y;
}
return x;
}
ki calc(int l,int r){
return {pref[r]-pref[l-1],(r-l+1)};
}
ki ans={1000000000,1};
void test(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
pref[i]=pref[i-1]+a[i];
}
set<tuple<ki,int,int>>s;
int l=1;
int r=n;
ki mx=calc(1,n);
while(1){
s.insert({calc(l,r),l,r});
if(l==r)break;
if(calc(l+1,r)<=mx)l++;
else r--;
}
while(1){
auto [w,tl,tr]=*s.begin();
s.erase(s.begin());
ans=min(ans,mx-w);
if(tr==n)break;
s.insert({calc(tl+1,tr+1),tl+1,tr+1});
mx=max(mx,calc(tl+1,tr+1));
}
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();
}
}
