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