import java.util.*;

public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.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