import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.nextLine());
		List<Double> v = new ArrayList<>();
		for (int i = 0; i < N; i++) {
			v.add(sc.nextDouble());
		}
		v.sort(null);
		while (v.size() > 1) {
			double vv = (v.remove(0) + v.remove(0)) / 2;
			v.add(0, vv);
		}
		System.out.println(v.get(0));
	}
}
/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