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