import java.util.Arrays;
import java.util.Scanner;
public class Main {
 
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double sum =0;
		double a[] = new double [N];
		for(int i = 0;i<N;i++) {
			a[i]=sc.nextInt();
		}
        Arrays.sort(a);
		sum = (a[0]+a[1])/2;
		for(int b=2;b<N;b++) {
			sum=(sum+a[b])/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