#include <bits/stdc++.h>
#define all(a) a.begin(), a.end()
#define popcount(x) __builtin_popcountll(x)
using namespace std;
using namespace chrono;
int a[100];
long double avg[100][100];
bool active[100][100], visited[100][100];
bool dfs(int l, int r) {
if (!active[l][r] || visited[l][r]) return false;
if (l == r) return true;
visited[l][r] = true;
return dfs(l+1, r) | dfs(l, r-1);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
for (int i = 0; i < n; cin >> a[i++]);
// for (int i = 0; i < n; a[i++] = i);
for (int l = 0; l < n; l++) {
avg[l][l] = a[l];
for (int r = l+1; r < n; r++) {
avg[l][r] = avg[l][r-1] + a[r];
}
for (int r = l; r < n; r++)
avg[l][r] /= r-l+1;
}
vector<tuple<int,int,double>> nodes;
for (int l = 0; l < n; l++) {
for (int r = l; r < n; r++) {
nodes.emplace_back(l, r, avg[l][r]);
}
}
sort(all(nodes), [&](tuple<int,int,double> a, tuple<int,int,double> b) {
return get<2>(a) < get<2>(b);
});
int r = 0;
double ans = 1e9;
for (int l = 0; l < nodes.size(); l++) {
{
// auto [x, y, z] = nodes[l];
// cout<<x<<' '<<y<<' '<<z<<'\n';
}
while (r < nodes.size() && !dfs(0, n-1)) {
auto [x, y, z] = nodes[r++];
active[x][y] = true;
memset(visited, false, sizeof visited);
}
if (dfs(0, n-1)) {
auto [b, c, d] = nodes[l];
auto [e, f, g] = nodes[r-1];
ans = min(ans, g - d);
}
auto [x, y, z] = nodes[l];
active[x][y] = false;
}
cout << fixed << setprecision(10) << ans;
}
