#include <bits/stdc++.h>
using namespace std;
float x, a, b, c;
int main(int argc, char const* argv[]) {
  int m;
  cin >> m;
  x = 0;
  float quz = 1;
  float foo = 0, baz = 0, bar = 0;
  for (int i = 0; i < m; i += 1) {
    cin >> a;
    foo = foo + a;
    bar += 1;
    if (max(foo * quz, bar * baz) == foo * quz) {
      baz = foo;
      quz = bar;
    }
  }
  cout << baz / quz << '\n';
  return 0;
}
