import java.util.*;
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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
} import java.util.*; util.* java 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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
} 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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    } main {
        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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] v = new int[n]; v new int[n] n for(int i = 0 ; i < n ; i++ ){
            v[i] = sc.nextInt();
        } int i = 0 ; int i = 0 ; i 0 i < n i n i++ i++ i {
            v[i] = sc.nextInt();
        } {
            v[i] = sc.nextInt();
        } v[i] = sc.nextInt() v[i] v i sc.nextInt() sc.nextInt sc Arrays.sort(v) Arrays.sort Arrays v Double s = (v[0] + v[1]) * 1.0; s (v[0] + v[1]) * 1.0 (v[0] + v[1]) v[0] v 0 v[1] v 1 1.0 for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        } int i = 2 ; int i = 2 ; i 2 i < n i n i++ i++ i {
            s = s + v[i] * Math.pow(2 , i - 1);
        } {
            s = s + v[i] * Math.pow(2 , i - 1);
        } s = s + v[i] * Math.pow(2 , i - 1) s s + v[i] * Math.pow(2 , i - 1) s v[i] * Math.pow(2 , i - 1) v[i] v i Math.pow(2 , i - 1) Math.pow Math 2 i - 1 i 1 System.out.println(s * 1.0 / Math.pow(2 , n - 1)) System.out.println System.out System System.out s * 1.0 / Math.pow(2 , n - 1) s * 1.0 s 1.0 Math.pow(2 , n - 1) Math.pow Math 2 n - 1 n 1 String[] args args 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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
} 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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
} Main
import java.util.*;
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 s = (v[0] + v[1]) * 1.0;
        for(int i = 2 ; i < n ; i++ ){
            s = s + v[i] * Math.pow(2 , i - 1);
        }
        System.out.println(s * 1.0 / Math.pow(2 , n - 1));
    }
}