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