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

        Arrays.sort(a);

        double res = a[0];
        for(int i=1; i<n; i++) {
            res = (res + a[i]) / 2;
        }
        System.out.println(res);


    }

}
