
import java.util.Arrays;
import java.util.Scanner;

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

		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		double v[] = new double[n];

		for (int i = 0; i < n; i++) {
			v[i] = sc.nextDouble();
		}
		sc.close();

		Arrays.sort(v);

		double s = (v[0] + v[1]) / 2;

		if (n >= 3) {
			for (int i = 2; i < n; i++) {

				s = (s + v[i]) / 2;

			}
		}
		System.out.println(s);

	}
}
/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