import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) throws Exception
	{
		new Main().run();
	}
	
	public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	}
} import java.util.PriorityQueue; PriorityQueue java.util import java.util.Scanner; Scanner java.util public class Main {
	
	public static void main(String[] args) throws Exception
	{
		new Main().run();
	}
	
	public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	}
} Main public static void main(String[] args) throws Exception
	{
		new Main().run();
	} main {
		new Main().run();
	} new Main().run() new Main().run new Main() String[] args args public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	} run {
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	} Scanner file = new Scanner(System.in); file new Scanner(System.in) int N = file.nextInt(); N file.nextInt() file.nextInt file double[] ints = new double[N]; ints new double[N] N for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble(); int i = 0; int i = 0; i 0 i<N i N i++ i++ i ints[i] = file.nextDouble(); ints[i] = file.nextDouble() ints[i] ints i file.nextDouble() file.nextDouble file PriorityQueue<Double> que = new PriorityQueue<Double>(); que new PriorityQueue<Double>() for(double x:ints)
			que.add(x); double x ints que.add(x); que.add(x) que.add que x while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		} que.size() != 1 que.size() que.size que 1 {
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		} double x= que.poll(); x que.poll() que.poll que double y = que.poll(); y que.poll() que.poll que que.offer((x+y)/2) que.offer que (x+y)/2 (x+y) x y 2 System.out.println(que.peek()) System.out.println System.out System System.out que.peek() que.peek que public class Main {
	
	public static void main(String[] args) throws Exception
	{
		new Main().run();
	}
	
	public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	}
} public class Main {
	
	public static void main(String[] args) throws Exception
	{
		new Main().run();
	}
	
	public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	}
} Main
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) throws Exception
	{
		new Main().run();
	}
	
	public void run() throws Exception
	{
		Scanner file = new Scanner(System.in);
		int N = file.nextInt();
		double[] ints = new double[N];
		for(int i = 0;i<N;i++)
			ints[i] = file.nextDouble();
		PriorityQueue<Double> que = new PriorityQueue<Double>();
		for(double x:ints)
			que.add(x);
		while(que.size() != 1)
		{
			double x= que.poll();
			double y = que.poll();
			que.offer((x+y)/2);
		}
		System.out.println(que.peek());
	}
}
