#include <bits/stdc++.h>
using namespace std;
int main() {
  int tux;
  cin >> tux;
  double foo = 0;
  double bar = 0;
  double baz = 0;
  double quz = 0;
  for (; tux != 0; tux--) {
    int pur;
    cin >> pur;
    foo = pur + foo;
    bar = bar + 1;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  double quoshnt = baz / quz;
  cout << setprecision(10) << quoshnt;
  return 0;
}
