import java.util.Arrays;
import java.util.Scanner;

public class Main {
	static int intN =0;
	static int sosuCnt =0;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	}
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {
	static int intN =0;
	static int sosuCnt =0;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	}
} Main static int intN =0; intN 0 static int sosuCnt =0; sosuCnt 0 public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	} main {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String n = sc.nextLine(); n sc.nextLine() sc.nextLine sc String[] v = sc.nextLine().split(" "); v sc.nextLine().split(" ") sc.nextLine().split sc.nextLine() sc.nextLine sc " " int intN = Integer.parseInt(n); intN Integer.parseInt(n) Integer.parseInt Integer n int intV[] = new int[intN]; intV new int[intN] intN for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 } int i = 0; int i = 0; i 0 i < v.length i v.length v v.length i++ i++ i {
			    intV[i] = Integer.parseInt(v[i]);
		 } {
			    intV[i] = Integer.parseInt(v[i]);
		 } intV[i] = Integer.parseInt(v[i]) intV[i] intV i Integer.parseInt(v[i]) Integer.parseInt Integer v[i] v i Arrays.sort(intV) Arrays.sort Arrays intV double result = 0; result 0 for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		} int i = 0; int i = 0; i 0 i < intV.length-1 i intV.length-1 intV.length intV intV.length 1 i++ i++ i {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		} {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		} if (i==0) {
				result = intV[0];
			} i==0 i 0 {
				result = intV[0];
			} result = intV[0] result intV[0] intV 0 result = (result + intV[i+1])/2 result (result + intV[i+1])/2 (result + intV[i+1]) result intV[i+1] intV i+1 i 1 2 System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	static int intN =0;
	static int sosuCnt =0;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	}
} public class Main {
	static int intN =0;
	static int sosuCnt =0;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	}
} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	static int intN =0;
	static int sosuCnt =0;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String n = sc.nextLine();
		String[] v = sc.nextLine().split(" ");

		int intN = Integer.parseInt(n);
		int intV[] = new int[intN];
		 for(int i = 0; i < v.length; i++){
			    intV[i] = Integer.parseInt(v[i]);
		 }

		Arrays.sort(intV);

		double result = 0;
		for (int i = 0; i < intV.length-1; i++) {
			if (i==0) {
				result = intV[0];
			}

			result = (result + intV[i+1])/2;
		}



		System.out.println(result);
	}
}