import java.util.*;
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    LinkedList<Double> material = new LinkedList<Double>();
    for(int i = 0; i < n; i++){
      material.add(sc.nextDouble());
    }
    
    while(material.size() > 1){
      //降順にソートしてから前2つを取り出し生成物を1つプッシュ
      Collections.sort(material);
      material.add((material.pollFirst() + material.pollFirst()) / 2);
    }
    
    System.out.println(material.peek());
  }
  
}
/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