#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int a[100];
  cin >> n;
  int foo, bar, baz, quz;
  foo = 0;
  bar = 0;
  baz = 0;
  quz = 1;
  int pur;
  for (int i = 0; i < n; i++) {
    cin >> pur;
    foo = foo + pur;
    bar = bar + 1;
    if (foo * quz > bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  cout << (baz + 0.0) / (quz + 0.0) << endl;
  return 0;
}
