#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int tux;
  cin >> tux;
  int foo = 0, bar = 0, baz = 0, quz = 1;
  for (int i = 1; i <= tux; i += 1) {
    int pur;
    cin >> pur;
    foo += pur;
    bar += 1;
    if (foo * quz == max(foo * quz, bar * baz)) {
      baz = foo;
      quz = bar;
    }
  }
  cout << setprecision(5) << 1.0 * baz / quz << '\n';
  return 0;
}
