#include <bits/stdc++.h>
using namespace std;
int main() {
  int tux;
  cin >> tux;
  int foo, bar, baz, quz, pur, oo;
  foo = bar = baz = 0;
  quz = 1;
  while (tux) {
    cin >> pur;
    foo += pur;
    bar++;
    if (foo * quz > bar * baz) {
      baz = foo;
      quz = bar;
    }
    tux--;
  }
  cout.precision(5);
  cout << fixed << (baz * 1. / quz);
  return 0;
}
