#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  double arr[n];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + n);
  double pt = (double)arr[n - 1];
  reverse(arr, arr + n);
  for (int i = 1; i < n; i++) {
    pt = pt + arr[i];
    pt = pt / 2.0;
  }
  cout << setprecision(12) << pt;
}
