import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	}

	private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	}
} 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();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	}

	private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int[] value = new int[N]; value new int[N] N for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		} int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
			value[i] = sc.nextInt();
		} {
			value[i] = sc.nextInt();
		} value[i] = sc.nextInt() value[i] value i sc.nextInt() sc.nextInt sc value =  sort(value, N) value sort(value, N) sort value N double alchemyResult = ((double)value[0] + (double)value[1]) / 2; alchemyResult ((double)value[0] + (double)value[1]) / 2 ((double)value[0] + (double)value[1]) (double)value[0] value 0 (double)value[1] value 1 2 for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		} int i = 2; int i = 2; i 2 i < N i N i++ i++ i {
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		} {
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		} alchemyResult = (alchemyResult + (double)value[i]) / 2 alchemyResult (alchemyResult + (double)value[i]) / 2 (alchemyResult + (double)value[i]) alchemyResult (double)value[i] value i 2 System.out.println(alchemyResult) System.out.println System.out System System.out alchemyResult sc.close() sc.close sc String[] args args private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	} sort {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	} for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		} int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		} {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		} for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			} int j = N-1; int j = N-1; j N-1 N 1 0 <= j 0 j j-- j-- j {
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			} {
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			} if(i == j) break; i == j i j break; if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				} a[j] < a[j-1] a[j] a j a[j-1] a j-1 j 1 {
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				} int temp = a[j]; temp a[j] a j a[j] = a[j-1] a[j] a j a[j-1] a j-1 j 1 a[j-1] = temp a[j-1] a j-1 j 1 temp return a; a int[] a a int N N public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	}

	private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	}

	private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[] value = new int[N];
		for(int i = 0; i < N; i++)
		{
			value[i] = sc.nextInt();
		}

		value =  sort(value, N);

		double alchemyResult = ((double)value[0] + (double)value[1]) / 2;

		for(int i = 2; i < N; i++)
		{
			alchemyResult = (alchemyResult + (double)value[i]) / 2;
		}

		System.out.println(alchemyResult);
		sc.close();
	}

	private static int[] sort(int[] a, int N) {
		for(int i = 0; i < N; i++) {
			for(int j = N-1; 0 <= j; j--)
			{
				if(i == j) break;
				if(a[j] < a[j-1])
				{
					int temp = a[j];
					a[j] = a[j-1];
					a[j-1] = temp;
				}
			}
		}
		return a;
	}
}