import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int v[] = new int[n]; v new int[n] n for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt(); int i = 0; int i = 0; i 0 i < n i n ++i ++i i v[i] = sc.nextInt(); v[i] = sc.nextInt() v[i] v i sc.nextInt() sc.nextInt sc sc.close() sc.close sc Arrays.sort(v) Arrays.sort Arrays v long w = 1; w 1 double ans = 0.0; ans 0.0 for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		} int i = n - 1; int i = n - 1; i n - 1 n 1 i > 0 i 0 --i --i i {
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		} {
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		} w <<= 1 w 1 int tmp = v[i]; tmp v[i] v i ans += (double)tmp / (double)w ans (double)tmp / (double)w (double)tmp (double)w ans += (double)v[0] / (double)w ans (double)v[0] / (double)w (double)v[0] v 0 (double)w System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int v[] = new int[n];
		for(int i = 0; i < n; ++i)
		v[i] = sc.nextInt();
		sc.close();
		Arrays.sort(v);
		long w = 1;
		double ans = 0.0;
		for(int i = n - 1; i > 0; --i){
			w <<= 1;
			int tmp = v[i];
			ans += (double)tmp / (double)w;
		}
		ans += (double)v[0] / (double)w;
		System.out.println(ans);
	}
}
