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();
		int v[] = new int[N];

		for (int i = 0; i < N; i++) {
			v[i] = sc.nextInt();
		}
		Arrays.sort(v);
		double cal = v[0];
		for (int i = 1; i < N ; i++) {
			cal += v[i];
			cal /= 2;
		}
		System.out.println(cal);
	}
}
