#include <bits/stdc++.h>   using namespace std;   const int MAXN = 1e5;   int n;   double a[MAXN], b[4], t;   int main() {     ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);     cin >> n;     b[3] = 1;     for (int i = 1; i <= n; i++) {       cin >> t;       b[0] += t;       b[1]++;       if (b[1] * b[2] <= b[0] * b[3]) b[2] = b[0], b[3] = b[1];     }     cout << fixed << setprecision(10) << b[2] / b[3] << endl;     return 0;   }   