import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] v = new int[n];
        for(int i = 0 ; i < n ; i++ ){
            v[i] = sc.nextInt();
        }
        Arrays.sort(v);
        Double s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
}
/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