import java.util.Arrays;
import java.util.Scanner;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    double[] indegrients = new double[n];
    for(int i = 0; i < n; i++){
      indegrients[i] = Integer.parseInt(sc.next());
    }
    Arrays.sort(indegrients);
    for(int i = 0; i < n - 1; i++){
      indegrients[i + 1] = (indegrients[i] + indegrients[i + 1]) / 2.0;
    }
    System.out.println(indegrients[n - 1]);
  }
}
/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