import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    }
} 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();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc float a[] = new float[n]; a new float[n] n for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            a[i] = sc.nextFloat();
        } {
            a[i] = sc.nextFloat();
        } a[i] = sc.nextFloat() a[i] a i sc.nextFloat() sc.nextFloat sc float tmp = 0; tmp 0 for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        } {
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        } for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            } int j = i + 1; int j = i + 1; j i + 1 i 1 j < n j n j++ j++ j {
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            } {
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            } if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                } a[i] > a[j] a[i] a i a[j] a j {
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                } tmp = a[i] tmp a[i] a i a[i] = a[j] a[i] a i a[j] a j a[j] = tmp a[j] a j tmp float r = (a[0] + a[1]) / 2; r (a[0] + a[1]) / 2 (a[0] + a[1]) a[0] a 0 a[1] a 1 2 for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        } int i = 2; int i = 2; i 2 i < n i n i++ i++ i {
            r = (r + a[i]) / 2;
        } {
            r = (r + a[i]) / 2;
        } r = (r + a[i]) / 2 r (r + a[i]) / 2 (r + a[i]) r a[i] a i 2 System.out.println(r) System.out.println System.out System System.out r String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        float a[] = new float[n];
        for(int i = 0; i < n; i++){
            a[i] = sc.nextFloat();
        }
        float tmp = 0;
        for(int i = 0; i < n; i++){
            for(int j = i + 1; j < n; j++){
                if(a[i] > a[j]){
                    tmp = a[i];
                    a[i] = a[j];
                    a[j] = tmp;
                }
            }
        }
        float r = (a[0] + a[1]) / 2;
        for(int i = 2; i < n; i++){
            r = (r + a[i]) / 2;
        }
        System.out.println(r);
    }
}