import java.util.Scanner;
class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    }
}

/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