import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Queue<Double> pque = new PriorityQueue<>();
        for(int i = 0; i < n; i++) pque.add(sc.nextDouble());
        while(pque.size() > 1) {
            double tmp = (pque.poll() + pque.poll()) / 2.0;
            pque.add(tmp);
        }
        System.out.println(pque.poll());
    }
}

/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