import java.util.*;
 
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    }
    
    static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    }
    
    static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    }
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    } main {
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc double v[] = new double[n]; v new double[n] n for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            v[i] = sc.nextDouble();
        } {
            v[i] = sc.nextDouble();
        } v[i] = sc.nextDouble() v[i] v i sc.nextDouble() sc.nextDouble sc quick_sort(v, 0, n-1) quick_sort v 0 n-1 n 1 double sum = (v[0] + v[1]) / 2; sum (v[0] + v[1]) / 2 (v[0] + v[1]) v[0] v 0 v[1] v 1 2 for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        } int i = 2; int i = 2; i 2 i < n i n i++ i++ i {
            sum = (sum + v[i]) / 2;
        } {
            sum = (sum + v[i]) / 2;
        } sum = (sum + v[i]) / 2 sum (sum + v[i]) / 2 (sum + v[i]) sum v[i] v i 2 System.out.println(sum) System.out.println System.out System System.out sum String[] args args static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    } quick_sort {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    } if (left>=right) {
            return;
        } left>=right left right {
            return;
        } return; int p = (int)d[(left+right)/2]; p (int)d[(left+right)/2] d (left+right)/2 (left+right) left right 2 int l = left l left r = right r right tmp; tmp while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        } l<=r l r {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        } while(d[l] < p) { l++; } d[l] < p d[l] d l p { l++; } l++ l while(d[r] > p) { r--; } d[r] > p d[r] d r p { r--; } r-- r if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            } l<=r l r {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            } tmp = (int)d[l] tmp (int)d[l] d l d[l] = d[r] d[l] d l d[r] d r d[r] = tmp d[r] d r tmp l++ l r-- r quick_sort(d, left, r) quick_sort d left r quick_sort(d, l, right) quick_sort d l right double[] d d int left left int right right public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    }
    
    static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    }
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    }
    
    static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    }
} Main
import java.util.*;
 
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        double v[] = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }

        quick_sort(v, 0, n-1);

        double sum = (v[0] + v[1]) / 2;

        for (int i = 2; i < n; i++) {
            sum = (sum + v[i]) / 2;
        }

        System.out.println(sum);
    }
    
    static void quick_sort(double[] d, int left, int right) {
        if (left>=right) {
            return;
        }
        int p = (int)d[(left+right)/2];
        int l = left, r = right, tmp;
        while(l<=r) {
            while(d[l] < p) { l++; }
            while(d[r] > p) { r--; }
            if (l<=r) {
                tmp = (int)d[l]; d[l] = d[r]; d[r] = tmp;
                l++; r--;
            }
        }
        quick_sort(d, left, r);  // ピボットより左側をクイックソート
        quick_sort(d, l, right); // ピボットより右側をクイックソート
    }
}
