import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    ArrayList<Double> list = new ArrayList<Double>();

    for (int i = 0; i < n; i++) {
      list.add(sc.nextDouble());
    }

    for (int i = 0; i < (n - 1); i++) {
      Collections.sort(list);
      list.add((list.get(0) + list.get(1)) / 2);
      list.remove(0);
      list.remove(0);
    }

    System.out.println(list.get(0));

  }
}
/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