#include <bits/stdc++.h>
using namespace std;
int main() {
  std::cout << std::setprecision(6) << std::fixed;
  double tux;
  cin >> tux;
  double foo = 0, bar = 0, baz = 0, quz = 1;
  for (; tux != 0.0; tux--) {
    double pur;
    cin >> pur;
    foo = foo + pur;
    bar = bar + 1;
    if ((foo * quz) >= (bar * baz)) {
      baz = foo;
      quz = bar;
    }
  }
  cout << (double)(baz / quz);
  return 0;
}
