import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    } main {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a1 = scan.nextInt(); a1 scan.nextInt() scan.nextInt scan float total = 0; total 0 float f[] = new float[50]; f new float[50] 50 for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        } int i = 0; int i = 0; i 0 i < a1 i a1 i++ i++ i {
            f[i] = scan.nextFloat();
            total += 1/f[i];
        } {
            f[i] = scan.nextFloat();
            total += 1/f[i];
        } f[i] = scan.nextFloat() f[i] f i scan.nextFloat() scan.nextFloat scan total += 1/f[i] total 1/f[i] 1 f[i] f i Arrays.sort(f) Arrays.sort Arrays f float vv = 0; vv 0 for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        } float i f {
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        } {
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        } if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            } i!=0 i 0 {
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            } if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                } vv == 0 vv 0 {
                    vv= i;
                } vv= i vv i {
                    vv = (vv+i)/2;
                } vv = (vv+i)/2 vv (vv+i)/2 (vv+i) vv i 2 System.out.println(vv) System.out.println System.out System System.out vv String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scan = new Scanner(System.in);
        int a1 = scan.nextInt();
        float total = 0;
        float f[] = new float[50];
        for(int i = 0; i < a1; i++){
            f[i] = scan.nextFloat();
            total += 1/f[i];
        }
        Arrays.sort(f);
        float vv = 0; 
        for(float i :f){
            if(i!=0){
                if(vv == 0){
                    vv= i;
                }
                else{
                    vv = (vv+i)/2;
                }
            }
        }
        
        System.out.println(vv);
    }
}
