#include <bits/stdc++.h>
using namespace std;
int n;
double ans = 0, mx;
int main() {
  cin >> n;
  double l = n;
  for (int i = 1; i <= n; i++) {
    double k;
    cin >> k;
    ans += k;
    mx = max(ans / i, mx);
  }
  cout << fixed << setprecision(6) << mx;
}
