import java.io.*;
import java.util.*;
public class Main{
  public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);}
  } import java.io.*; io.* java import java.util.*; util.* java public class Main{
  public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);}
  } Main public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);} main {
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);} BufferedReader reader = new BufferedReader( new InputStreamReader(System.in)); reader new BufferedReader( new InputStreamReader(System.in)) int a = Integer.parseInt(reader.readLine()); a Integer.parseInt(reader.readLine()) Integer.parseInt Integer reader.readLine() reader.readLine reader double r = 0.0; r 0.0 int[] list =new int[a]; list new int[a] a String[] s =  reader.readLine().split(" "); s reader.readLine().split(" ") reader.readLine().split reader.readLine() reader.readLine reader " " for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);} int i =0; int i =0; i 0 i<a i a i++ i++ i {
      list[i] = Integer.parseInt(s[i]);} {
      list[i] = Integer.parseInt(s[i]);} list[i] = Integer.parseInt(s[i]) list[i] list i Integer.parseInt(s[i]) Integer.parseInt Integer s[i] s i Arrays.sort(list) Arrays.sort Arrays list r = ((double)list[0]+(double)list[1])/2.0 r ((double)list[0]+(double)list[1])/2.0 ((double)list[0]+(double)list[1]) (double)list[0] list 0 (double)list[1] list 1 2.0 for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;} int i =2; int i =2; i 2 i<a i a i++ i++ i {
 		r = (r+list[i])/2.0;} {
 		r = (r+list[i])/2.0;} r = (r+list[i])/2.0 r (r+list[i])/2.0 (r+list[i]) r list[i] list i 2.0 System.out.println(r) System.out.println System.out System System.out r String[] args args public class Main{
  public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);}
  } public class Main{
  public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);}
  } Main
import java.io.*;
import java.util.*;
public class Main{
  public static void main(String[] args) throws IOException{
    BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
    int a = Integer.parseInt(reader.readLine());
    double r = 0.0;
    int[] list =new int[a];
    String[] s =  reader.readLine().split(" ");
    for(int i =0;i<a;i++){
      list[i] = Integer.parseInt(s[i]);}
    Arrays.sort(list);
    r = ((double)list[0]+(double)list[1])/2.0;
    for(int i =2;i<a;i++){
 		r = (r+list[i])/2.0;}
      System.out.println(r);}
  }