import java.util.*;
import java.io.*;

public class Main
{
	public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	}
}
	 import java.util.*; util.* java import java.io.*; io.* java public class Main
{
	public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	}
} Main public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	} main {
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	} Scanner in = new Scanner(System.in); in new Scanner(System.in) int n=in.nextInt(); n in.nextInt() in.nextInt in ArrayList<Double> a=new ArrayList<Double>(); a new ArrayList<Double>() for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			a.add(in.nextDouble());
		} {
			a.add(in.nextDouble());
		} a.add(in.nextDouble()) a.add a in.nextDouble() in.nextDouble in Collections.sort(a) Collections.sort Collections a for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		} int i=0; int i=0; i 0 i<n-1 i n-1 n 1 i++ i++ i {
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		} {
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		} double temp=(a.get(0)+a.get(1))/2.0; temp (a.get(0)+a.get(1))/2.0 (a.get(0)+a.get(1)) a.get(0) a.get a 0 a.get(1) a.get a 1 2.0 a.remove(0) a.remove a 0 a.remove(0) a.remove a 0 a.add(temp) a.add a temp Collections.sort(a) Collections.sort Collections a System.out.println(a.get(0)) System.out.println System.out System System.out a.get(0) a.get a 0 String [] Args Args public class Main
{
	public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	}
} public class Main
{
	public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	}
} Main
import java.util.*;
import java.io.*;

public class Main
{
	public static void main(String [] Args)
	{
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		ArrayList<Double> a=new ArrayList<Double>();
		for(int i=0;i<n;i++)
		{
			a.add(in.nextDouble());
		}
		Collections.sort(a);
		for(int i=0;i<n-1;i++)
		{
			double temp=(a.get(0)+a.get(1))/2.0;
			a.remove(0);
			a.remove(0);
			a.add(temp);
			Collections.sort(a);
		}
		System.out.println(a.get(0));
	}
}
	