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

public class Main {

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	}

} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	}

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	} main {
	    Scanner scanner = new Scanner(System.in);

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int N = Integer.parseInt(scanner.next()); N Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner double[] S  = new double[N]; S new double[N] N for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    } int i=0; int i=0; i 0 i<N i N i++ i++ i {
	        S[i]= Double.parseDouble(scanner.next());
	    } {
	        S[i]= Double.parseDouble(scanner.next());
	    } S[i]= Double.parseDouble(scanner.next()) S[i] S i Double.parseDouble(scanner.next()) Double.parseDouble Double scanner.next() scanner.next scanner Arrays.parallelSort(S) Arrays.parallelSort Arrays S double m=(S[0] + S[1]) /2; m (S[0] + S[1]) /2 (S[0] + S[1]) S[0] S 0 S[1] S 1 2 for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    } int i=2; int i=2; i 2 i<N i N i++ i++ i {
	        m = (m+S[i]) / 2;
	    } {
	        m = (m+S[i]) / 2;
	    } m = (m+S[i]) / 2 m (m+S[i]) / 2 (m+S[i]) m S[i] S i 2 System.out.print(m) System.out.print System.out System System.out m String[] args args public class Main {

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	}

} public class Main {

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	}

} Main
import java.util.Arrays;
import java.util.Scanner;

public class Main {

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

	    int N = Integer.parseInt(scanner.next());
	    double[] S  = new double[N];
	    
	    for (int i=0; i<N; i++) {
	        S[i]= Double.parseDouble(scanner.next());
	    }
	    
	    Arrays.parallelSort(S);

	    double m=(S[0] + S[1]) /2;
        for (int i=2; i<N; i++) {
	        m = (m+S[i]) / 2;
	    }

        System.out.print(m);
	}

}