// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
- insert(x),erase(x)
- find_by_order(k): return iterator to the k-th smallest element
- order_of_key(x): the number of elements that are strictly smaller
*/
#include<bits/stdc++.h>
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
uniform_real_distribution<> pp(0.0,1.0);
#define int long long
#define ld long double
#define pii pair<int,int>
#define piii pair<int,pii>
#define mpp make_pair
#define fi first
#define se second
const int inf=1e9;
const int mod=998244353;
const int maxn=200005;
const int bl=650;
const int maxs=655;
const int maxm=200005;
const int maxq=1000005;
const int maxl=25;
const int maxa=1000000;
const int root=3;
int power(int a,int n){
int res=1;
while(n){
if(n&1) res=res*a%mod;
a=a*a%mod;n>>=1;
}
return res;
}
const int iroot=power(3,mod-2);
const int base=131;
int n,a[maxn],c[maxn],cnt;
void solve(){
cin >> n;
for(int i=1;i<=n;i++) cin >> a[i],a[i]+=a[i-1];
auto query = [&](int l,int r){
return (double)(a[r]-a[l-1])/(r-l+1);
};
double x=query(1,n);
vector<pair<double,int>> d;
for(int i=1;i<=n;i++){
int l=0,r=n-i,pos=-1;
while(l<=r){
int mid=(l+r)>>1;
if(query(mid+1,mid+i)<=x) pos=mid,l=mid+1;
else r=mid-1;
}
if(pos>=0) d.push_back({query(pos+1,pos+i),i});
if(pos<n-i) d.push_back({query(pos+2,pos+i+1),i});
}
sort(d.begin(),d.end());
double res=inf;
int p=0;
for(int i=0;i<(int)d.size();i++){
while(cnt<n && p<(int)d.size()){
int t=d[p].se;
cnt+=!c[t];
c[t]++;p++;
}
if(cnt==n) res=min(res,d[p-1].fi-d[i].fi);
int t=d[i].se;c[t]--;
cnt-=!c[t];
}
cout << setprecision(10) << fixed << res << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
int test=1;//cin >> test;
while(test--) solve();
}
