

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[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    }
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    } main {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int[] arr = new int[N]; arr new int[N] N for(int i = 0; i < N; i++) arr[i] = sc.nextInt(); int i = 0; int i = 0; i 0 i < N i N i++ i++ i arr[i] = sc.nextInt(); arr[i] = sc.nextInt() arr[i] arr i sc.nextInt() sc.nextInt sc Arrays.sort(arr) Arrays.sort Arrays arr double res = 0; res 0 double tmp = (double)(arr[0] + arr[1])/2; tmp (double)(arr[0] + arr[1])/2 (double)(arr[0] + arr[1]) arr[0] arr 0 arr[1] arr 1 2 for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        } int i = 2; int i = 2; i 2 i < N i N i++ i++ i {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        } {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        } if(arr.length == 2) break; arr.length == 2 arr.length arr arr.length 2 break; tmp = (tmp + arr[i]) / 2 tmp (tmp + arr[i]) / 2 (tmp + arr[i]) tmp arr[i] arr i 2 System.out.println(tmp) System.out.println System.out System System.out tmp String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    }
} Main


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[] arr = new int[N];
        for(int i = 0; i < N; i++) arr[i] = sc.nextInt();
        Arrays.sort(arr);
        double res = 0;
        double tmp = (double)(arr[0] + arr[1])/2;
        for(int i = 2; i < N; i++) {
            if(arr.length == 2) break;
            tmp = (tmp + arr[i]) / 2;
        }
        System.out.println(tmp);
    }
}
