import java.util.Scanner;
import java.util.Arrays;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
}
/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