import java.util.Collections;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	public static void main(String args[]){

		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		LinkedList<Integer> inputs = new LinkedList<>();

		for(int i=0;i < n;i++) {
			inputs.add(sc.nextInt());
		}
		Collections.sort(inputs);

		double beforeParam = inputs.pop();
		for(int i=0;i < n - 1;i++) {
			beforeParam = (beforeParam + inputs.pop()) / 2;
		}

		System.out.println(beforeParam);

	}
}
/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