import java.util.*;
import java.io.*;

public class Main {

	public void go() {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();

		PriorityQueue<Double> queue = new PriorityQueue<>();
		for (int i = 0; i < x; i++) {
			queue.add(sc.nextDouble());
		}

		while (queue.size() != 1) {
			Double a = queue.poll();
			Double b = queue.poll();
			queue.add((a + b) / 2);
		}

		System.out.println(queue.poll());

	}

	public static void main(String[] args) throws IOException {

		Main m = new Main();
		m.go();
	}

}

/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