import java.util.*;
import java.util.PriorityQueue;

public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    PriorityQueue<Double> q = new PriorityQueue<Double>();
    for(int i = 0; i < n; ++i)
    {
      double x = sc.nextDouble();
      q.add(x);
    }
    while(q.size() > 1)
    {
      double a = q.poll();
      double b = q.poll();
      q.add((a+b)/2.0);
    }
    double ans = q.poll();

    System.out.println(ans);
  }

}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz