import java.util.*;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int N = sc.nextInt();
   int[] Si = new int[N];
   for(int i = 0; i<N;i++)
   {
		Si[i] = sc.nextInt();       
   }
   Arrays.sort(Si);
   double half = ((double)Si[0]+(double)Si[1])/2;
   for(int i = 2; i<N;i++)
   {
		half = (half+(double)Si[i])/2;
   }
   System.out.println(half);
 }
}
/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