import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    } main {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan List<Double> v = new ArrayList<>(); v new ArrayList<>() for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            v.add(scan.nextDouble());
        } {
            v.add(scan.nextDouble());
        } v.add(scan.nextDouble()) v.add v scan.nextDouble() scan.nextDouble scan Collections.sort(v) Collections.sort Collections v double sum = 0; sum 0 double a = 0; a 0 while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        } v.size() > 1 v.size() v.size v 1 {
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        } a = (v.get(0) + v.get(1)) / 2 a (v.get(0) + v.get(1)) / 2 (v.get(0) + v.get(1)) v.get(0) v.get v 0 v.get(1) v.get v 1 2 v.remove(0) v.remove v 0 v.remove(0) v.remove v 0 v.add(a) v.add v a Collections.sort(v) Collections.sort Collections v System.out.println(v.get(0)) System.out.println System.out System System.out v.get(0) v.get v 0 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.get(0));
    }
}