import java.util.*;
public class Main{
  public static void main(String[]args){
    Scanner sc = new Scanner(System.in);

    int N = sc.nextInt();
    double[] data = new double[1000];
    int v;
    double temp;
    double lenkin;

    for(int i = 0;i<N;i++){

      v  = sc.nextInt();

      data[i]=v;

    }

    for(int i = 0;i<N;i++){
      for(int j = i+1;j<N;j++){
        if(data[i]>data[j]){
          temp = data[i];
          data[i]=data[j];
          data[j]=temp;
        }
      }
    }

    lenkin = (data[0]+data[1])/2;

    for(int i = 2;i<N;i++){
      lenkin = (lenkin+data[i])/2;

    }

    System.out.println(lenkin);

  }
}

/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