import java.util.*;
import java.util.TreeMap;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  }
} import java.util.*; util.* java import java.util.TreeMap; TreeMap java.util public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc double ans = 0; ans 0 ArrayList<Double> list = new ArrayList<>(); list new ArrayList<>() for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
      list.add(sc.nextDouble());
    } {
      list.add(sc.nextDouble());
    } list.add(sc.nextDouble()) list.add list sc.nextDouble() sc.nextDouble sc while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    } !(list.size() == 1) (list.size() == 1) list.size() list.size list 1 {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    } Collections.sort(list) Collections.sort Collections list double total = 0; total 0 total = (list.get(0) + list.get(1)) / 2 total (list.get(0) + list.get(1)) / 2 (list.get(0) + list.get(1)) list.get(0) list.get list 0 list.get(1) list.get list 1 2 list.remove(0) list.remove list 0 list.remove(0) list.remove list 0 list.add(total) list.add list total System.out.println(list.get(0)) System.out.println System.out System System.out list.get(0) list.get list 0 String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  }
} Main
import java.util.*;
import java.util.TreeMap;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    // double A[] = new double[N];
    double ans = 0;
    ArrayList<Double> list = new ArrayList<>();
    for (int i = 0; i < N; i++) {
      list.add(sc.nextDouble());
    }
    while (!(list.size() == 1)) {
      Collections.sort(list);
      double total = 0;
      total = (list.get(0) + list.get(1)) / 2;
      list.remove(0);
      list.remove(0);
      list.add(total);
    }
    System.out.println(list.get(0));
  }
}
