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