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