import java.util.Scanner;
class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    }
} import java.util.Scanner; Scanner java.util class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    }
} Main public static void main(String[]args){
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    } main {
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    } Scanner scan = new Scanner (System.in); scan new Scanner (System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int [] v = new int[n]; v new int[n] n for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        } int i =0; int i =0; i 0 i < n i n i++ i++ i {
            v[i] = scan.nextInt();
        } {
            v[i] = scan.nextInt();
        } v[i] = scan.nextInt() v[i] v i scan.nextInt() scan.nextInt scan for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        } int i = 0; int i = 0; i 0 i < n-1 i n-1 n 1 i++ i++ i {
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        } {
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        } for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            } int t = 0; int t = 0; t 0 t < n-1-i t n-1-i n-1-i n 1 i t++ t++ t {
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            } {
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            } if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                } v[t] > v[t+1] v[t] v t v[t+1] v t+1 t 1 {
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                } int keep = v[t]; keep v[t] v t v[t] = v[t+1] v[t] v t v[t+1] v t+1 t 1 v[t+1] = keep v[t+1] v t+1 t 1 keep double ans = (double)v[0]; ans (double)v[0] v 0 for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        } int i = 1; int i = 1; i 1 i < n i n i++ i++ i {
        	ans = (ans + (double)v[i]) / 2.0;
        } {
        	ans = (ans + (double)v[i]) / 2.0;
        } ans = (ans + (double)v[i]) / 2.0 ans (ans + (double)v[i]) / 2.0 (ans + (double)v[i]) ans (double)v[i] v i 2.0 System.out.println(ans) System.out.println System.out System System.out ans String[]args args
import java.util.Scanner;
class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner (System.in);
        int n = scan.nextInt();
        int [] v = new int[n];
        for(int i =0;i < n;i++){
            v[i] = scan.nextInt();
        }
        for(int i = 0;i < n-1;i++){
            for(int t = 0;t < n-1-i;   t++){
                if(v[t] > v[t+1]){
                    int keep = v[t];
                    v[t] = v[t+1];
                    v[t+1] = keep;
                }
            }
        }
        double ans = (double)v[0];
        for(int i = 1; i < n;i++) {
        	ans = (ans + (double)v[i]) / 2.0;
        }
        System.out.println(ans);
    }
}
