#include <bits/stdc++.h>
using namespace std;
int n;
double a, b, maximum;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a;
    b += a;
    maximum = max(maximum, (b / i));
  }
  cout << maximum;
  return 0;
}
