import java.util.*;

public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	}
} import java.util.*; util.* java public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	}
} Main public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc double[] d = new double[N]; d new double[N] N Queue<Double> queue = new PriorityQueue<>(); queue new PriorityQueue<>() for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		} int i = 0 ; int i = 0 ; i 0 i < N i N i++ i++ i {
			queue.add(sc.nextDouble());
		} {
			queue.add(sc.nextDouble());
		} queue.add(sc.nextDouble()) queue.add queue sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		} int i = 0; int i = 0; i 0 i < N - 1 i N - 1 N 1 i++ i++ i {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		} {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		} double d1 = queue.poll(); d1 queue.poll() queue.poll queue double d2 = queue.poll(); d2 queue.poll() queue.poll queue queue.add((d1+d2)/2) queue.add queue (d1+d2)/2 (d1+d2) d1 d2 2 System.out.println(queue.poll()) System.out.println System.out System System.out queue.poll() queue.poll queue String args[] args public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	}
} public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	}
} Main
import java.util.*;

public class Main{
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] d = new double[N];
		Queue<Double> queue = new PriorityQueue<>();
		for(int i = 0 ;i < N; i++) {
			queue.add(sc.nextDouble());
		}
		sc.close();
		
		for(int i = 0; i < N - 1; i++) {
			double d1 = queue.poll();
			double d2 = queue.poll();
			queue.add((d1+d2)/2);
		}
		System.out.println(queue.poll());
	}
}