#include <bits/stdc++.h>
using namespace std;
int tux, foo, bar, baz, quz = 1, pur;
int main() {
  ios::sync_with_stdio(0);
  cin >> tux;
  for (int i = 0; i < tux; ++i) {
    cin >> pur;
    foo += pur;
    ++bar;
    if (foo * quz > baz * bar) {
      baz = foo;
      quz = bar;
    }
  }
  cout << setprecision(6) << fixed << double(baz) / quz;
  return 0;
}
