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

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	}
} import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.List; List 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 = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	} main {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = Integer.parseInt(sc.next()); N Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc Double[] in = new Double[N]; in new Double[N] N for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next()); int i = 0; int i = 0; i 0 i < N i N i++ i++ i in[i] = Double.parseDouble(sc.next()); in[i] = Double.parseDouble(sc.next()) in[i] in i Double.parseDouble(sc.next()) Double.parseDouble Double sc.next() sc.next sc List<Double> list = new ArrayList<>(Arrays.asList(in)); list new ArrayList<>(Arrays.asList(in)) for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		} int i = 0; int i = 0; i 0 i < N-1 i N-1 N 1 i++ i++ i {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		} {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		} Collections.sort(list) Collections.sort Collections list Double val = (list.get(0) + list.get(1)) / 2; val (list.get(0) + list.get(1)) / 2 (list.get(0) + list.get(1)) list.get(0) list.get list 0 list.get(1) list.get list 1 2 list.remove(0) list.remove list 0 list.remove(0) list.remove list 0 list.add(val) list.add list val System.out.println(list.get(0)) System.out.println System.out System System.out list.get(0) list.get list 0 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	}
} Main
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		Double[] in = new Double[N];
		
		for (int i = 0; i < N; i++) in[i] = Double.parseDouble(sc.next());
		
		List<Double> list = new ArrayList<>(Arrays.asList(in));
		for (int i = 0; i < N-1; i++) {	
			Collections.sort(list);
			Double val = (list.get(0) + list.get(1)) / 2;
			list.remove(0);
			list.remove(0);
			list.add(val);
		}
		
		System.out.println(list.get(0));
	}
}
