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();

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  }

} 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();

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  }

} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc double[] v = new double[N]; v new double[N] N for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
      v[i] = sc.nextDouble();
    } {
      v[i] = sc.nextDouble();
    } v[i] = sc.nextDouble() v[i] v i sc.nextDouble() sc.nextDouble sc Arrays.sort(v) Arrays.sort Arrays v double sum = 0; sum 0 for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    } int i = N-1; int i = N-1; i N-1 N 1 i >=2 i 2 --i --i i {
      sum += v[i] / ((long)1 << N-i );
    } {
      sum += v[i] / ((long)1 << N-i );
    } sum += v[i] / ((long)1 << N-i ) sum v[i] / ((long)1 << N-i ) v[i] v i ((long)1 << N-i ) (long)1 N-i N i sum += (v[0]+v[1])/ ((long)1 << (N-1) ) sum (v[0]+v[1])/ ((long)1 << (N-1) ) (v[0]+v[1]) v[0] v 0 v[1] v 1 ((long)1 << (N-1) ) (long)1 (N-1) N 1 System.out.println(sum) System.out.println System.out System System.out sum String[] args args public class Main {

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

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  }

} public class Main {

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

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  }

} 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();

    double[] v = new double[N];
    for (int i = 0; i < N; i++) {
      v[i] = sc.nextDouble();
    }
    Arrays.sort(v);

    double sum = 0;
    for (int i = N-1; i >=2 ; --i) {
      sum += v[i] / ((long)1 << N-i );
    }
    sum += (v[0]+v[1])/ ((long)1 << (N-1) );


    System.out.println(sum);


  }

}
