#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-8;
int sum = 0, n;
double ans = 0.0;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    sum += a;
    if (sum / (double)(i + 1) - ans > eps) {
      ans = sum / (double)(i + 1);
    }
  }
  printf("%.6lf\n", ans);
  return 0;
}
