#include <bits/stdc++.h>
using namespace std;
int t, f, br, bz, q = 1, p;
int main() {
  ios::sync_with_stdio(false);
  cin >> t;
  for (int i = 1; i <= t; ++i) {
    cin >> p;
    f += p;
    br++;
    if (f * q > bz * br) bz = f, q = br;
  }
  cout << double(1.0 * bz / q) << endl;
  return 0;
}
