import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	}

} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	} main {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n= scan.nextInt(); n scan.nextInt() scan.nextInt scan double v[]=new double[n]; v new double[n] n for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			v[i]=scan.nextDouble();
		} {
			v[i]=scan.nextDouble();
		} v[i]=scan.nextDouble() v[i] v i scan.nextDouble() scan.nextDouble scan scan.close() scan.close scan Arrays.sort(v) Arrays.sort Arrays v double ave=(v[0]+v[1])/2; ave (v[0]+v[1])/2 (v[0]+v[1]) v[0] v 0 v[1] v 1 2 for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		} int i=1; int i=1; i 1 i<n-1 i n-1 n 1 i++ i++ i {
			ave=(ave+v[i+1])/2;
		} {
			ave=(ave+v[i+1])/2;
		} ave=(ave+v[i+1])/2 ave (ave+v[i+1])/2 (ave+v[i+1]) ave v[i+1] v i+1 i 1 2 System.out.println(ave) System.out.println System.out System System.out ave String[] args args public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	}

} public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	}

} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n= scan.nextInt();
		double v[]=new double[n];
		for(int i=0;i<n;i++) {
			v[i]=scan.nextDouble();
		}
		scan.close();
		Arrays.sort(v);

		double ave=(v[0]+v[1])/2;
		for(int i=1;i<n-1;i++) {
			ave=(ave+v[i+1])/2;
		}
		System.out.println(ave);
	}

}