#include <bits/stdc++.h>
using namespace std;
int main() {
  int x;
  scanf("%d", &x);
  double sum = 0.0;
  double res = 0;
  for (int i = 0; i < (x); ++i) {
    int y;
    scanf("%d", &y);
    sum += y;
    res = max(res, sum / (i + 1));
  }
  printf("%.30lf\n", res);
}
