import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	}
} 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();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		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 double[] A = new double[N]; A new double[N] N double tmp; tmp double ans = 0; ans 0 for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			A[i] = sc.nextDouble();
 		} {
			A[i] = sc.nextDouble();
 		} A[i] = sc.nextDouble() A[i] A i sc.nextDouble() sc.nextDouble sc 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 for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		} {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		} ans += A[i]/Math.pow(2,N-i) ans A[i]/Math.pow(2,N-i) A[i] A i Math.pow(2,N-i) Math.pow Math 2 N-i N i if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			} i == 0 i 0 {
				ans += A[i]/Math.pow(2,N-i);
			} ans += A[i]/Math.pow(2,N-i) ans A[i]/Math.pow(2,N-i) A[i] A i Math.pow(2,N-i) Math.pow Math 2 N-i N i 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) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		double[] A = new double[N];
		double tmp;
		double ans = 0;
		for(int i=0;i<N;i++) {
			A[i] = sc.nextDouble();
 		}
		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;
				}
			}
		}
		for(int i=0;i<N;i++) {
			ans += A[i]/Math.pow(2,N-i);
			if(i == 0) {
				ans += A[i]/Math.pow(2,N-i);
			}
		}
		System.out.println(ans);
	}
}