import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

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

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

    }
} import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections java.util import java.util.List; List java.util 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();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

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

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

    } main {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc List<Double> values = new ArrayList<>(); values new ArrayList<>() for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            values.add(sc.nextDouble());
        } {
            values.add(sc.nextDouble());
        } values.add(sc.nextDouble()) values.add values sc.nextDouble() sc.nextDouble sc Collections.sort(values) Collections.sort Collections values double result = 0; result 0 for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        } int i = 0; int i = 0; i 0 i < n-1 i n-1 n 1 i++ i++ i {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        } {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        } double c = (values.get(i) + values.get(i+1)) / 2; c (values.get(i) + values.get(i+1)) / 2 (values.get(i) + values.get(i+1)) values.get(i) values.get values i values.get(i+1) values.get values i+1 i 1 2 result = c result c values.set(i+1, c) values.set values i+1 i 1 c System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

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

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

    }
} Main
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

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

        int n = sc.nextInt();

        List<Double> values = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            values.add(sc.nextDouble());
        }

        Collections.sort(values);

        double result = 0;
        for (int i = 0; i < n-1; i++) {
            double c = (values.get(i) + values.get(i+1)) / 2;
            result = c;
            values.set(i+1, c);
        }

        System.out.println(result);

    }
}
