import java.util.Scanner;
import java.util.Collections;
import java.util.List;
import java.util.ArrayList;
public class Main {
  public static void main(String... args) {
    Scanner scan = new Scanner(System.in);
    int count = scan.nextInt();
    List<Integer> list = new ArrayList<>();
    while (scan.hasNextInt()) {
      list.add(scan.nextInt());
    }
    Collections.sort(list);
    double x = 0;
    for (int num : list) {
      x = x==0?num:(num+x)/2;
    }
    System.out.println(x);
  }
}
/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