import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		ArrayList<Double> li = new ArrayList<Double>();
		for(int i = 0; i < N; i++) {
			li.add(sc.nextDouble());
		}
		Collections.sort(li);
		double sum = 0;
		for(int i = 1; i < N; i++) {
			if(i != 1) {
				sum = (sum + li.get(i)) / 2;
			}else {
				sum = (li.get(i) + li.get(i - 1)) / 2;
			}

		}
		System.out.println(sum);

	}

}
/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