import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double[] v = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextDouble();
        }
        Arrays.sort(v);
        for (int i = 1; i < n; i++) {
            v[i] = (v[i-1] + v[i])/2.0;
        }
        System.out.println(v[n-1]);
        sc.close();

    }

}
