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[] v = new double[n];
		double ans = 0;

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

		Arrays.sort(v);

		ans = (v[0] + v[1])/2;
		for(int i = 2; i < n; i++) {
			ans = (ans + v[i])/2;
		}

		System.out.println(String.format("%.5f", ans));

	}

}
/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