import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	}

} import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections 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 output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc double output = 0; output 0 ArrayList<Double> arr = new ArrayList<>(); arr new ArrayList<>() for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		} int i = 0; int i = 0; i 0 i<N i N i++ i++ i {
			arr.add(sc.nextDouble());
		} {
			arr.add(sc.nextDouble());
		} arr.add(sc.nextDouble()) arr.add arr sc.nextDouble() sc.nextDouble sc Collections.sort(arr) Collections.sort Collections arr while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		} arr.size()>1 arr.size() arr.size arr 1 {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		} double temp = (arr.get(0)+arr.get(1))/2; temp (arr.get(0)+arr.get(1))/2 (arr.get(0)+arr.get(1)) arr.get(0) arr.get arr 0 arr.get(1) arr.get arr 1 2 output=temp output temp arr.set(0, temp) arr.set arr 0 temp arr.remove(1) arr.remove arr 1 System.out.println(output) System.out.println System.out System System.out output String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	}

} Main
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double output = 0;
		ArrayList<Double> arr = new ArrayList<>();
		for(int i = 0;i<N;i++) {
			arr.add(sc.nextDouble());
		}
		Collections.sort(arr);
		while(arr.size()>1) {
			double temp = (arr.get(0)+arr.get(1))/2;
			//System.out.println(temp);
			output=temp;
			arr.set(0, temp);
			arr.remove(1);	
		}
		System.out.println(output);
		
		
		

	}

}
