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 ans = (double)v[0];
		for(int i=1;i<N;i++) {
			ans = (ans + (double)v[i])/2.0;
		}

		System.out.println(ans);
	}

}
