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

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	}
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] array = new int[n]; array new int[n] n for(int i = 0; i < n; i++)
			array[i] = sc.nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i array[i] = sc.nextInt(); array[i] = sc.nextInt() array[i] array i sc.nextInt() sc.nextInt sc Arrays.sort(array) Arrays.sort Arrays array double ans = (array[0] + array[1]) / 2.0; ans (array[0] + array[1]) / 2.0 (array[0] + array[1]) array[0] array 0 array[1] array 1 2.0 for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0; int i = 2; int i = 2; i 2 i < n i n i++ i++ i ans = (array[i] + ans) / 2.0; ans = (array[i] + ans) / 2.0 ans (array[i] + ans) / 2.0 (array[i] + ans) array[i] array i ans 2.0 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	}
} Main
import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int[] array = new int[n];
		for(int i = 0; i < n; i++)
			array[i] = sc.nextInt();
		Arrays.sort(array);
		
		double ans = (array[0] + array[1]) / 2.0;
		for(int i = 2; i < n; i++)
			ans = (array[i] + ans) / 2.0;
		
		System.out.println(ans);
	}
}
