import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    }
} import java.lang.reflect.Array; Array java.lang.reflect import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.Comparator; Comparator 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();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    } main {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc Float[] a = new Float[N]; a new Float[N] N for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt(); int i = 0; int i = 0; i 0 i < N i N i++ i++ i a[i] = (float) sc.nextInt(); a[i] = (float) sc.nextInt() a[i] a i (float) sc.nextInt() sc.nextInt sc float sum = 0.0f; sum 0.0f Arrays.sort(a, Comparator.reverseOrder()) Arrays.sort Arrays a Comparator.reverseOrder() Comparator.reverseOrder Comparator for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            sum += a[i] / Math.pow(2, i);
        } {
            sum += a[i] / Math.pow(2, i);
        } sum += a[i] / Math.pow(2, i) sum a[i] / Math.pow(2, i) a[i] a i Math.pow(2, i) Math.pow Math 2 i sum += a[N - 1] / Math.pow(2, N-1) sum a[N - 1] / Math.pow(2, N-1) a[N - 1] a N - 1 N 1 Math.pow(2, N-1) Math.pow Math 2 N-1 N 1 System.out.println(sum / 2) System.out.println System.out System System.out sum / 2 sum 2 String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    }
} Main
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        Float[] a = new Float[N];
        for (int i = 0; i < N; i++)
            a[i] = (float) sc.nextInt();
        float sum = 0.0f;

        Arrays.sort(a, Comparator.reverseOrder());

        for (int i = 0; i < N; i++) {
            sum += a[i] / Math.pow(2, i);
        }

        sum += a[N - 1] / Math.pow(2, N-1);

        System.out.println(sum / 2);
    }
}