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