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];

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

		Arrays.sort(v);
		double answer = v[0];

		for (int i = 0; i < N - 1; i++) {
			answer = (answer + v[i + 1]) / 2;
		}

		System.out.println(answer);
	}
}
