#include <bits/stdc++.h>
int n;
double sum, tmp, ans;
int main() {
  scanf("%d", &n);
  for (int div = 1; div <= n; div++) {
    scanf("%lf", &tmp);
    sum += tmp;
    if (sum / div > ans) ans = sum / div;
  }
  printf("%.20lf\n", ans);
}
