#include <bits/stdc++.h>
using namespace std;
int main() {
  double tux, pur, foo = 0, bar = 0, baz = 0, quz = 1;
  cin >> tux;
  for (register int i = 1; i <= tux; ++i) {
    cin >> pur;
    foo += pur, bar++;
    if (foo * quz > baz * bar) baz = foo, quz = bar;
  }
  return printf("%.6lf", baz / quz) % 1;
}
