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);
        //System.out.println(Arrays.toString(v));
        double sum = v[0];
        for(int i = 1; i < N; i++){
            sum = (sum + v[i])/2;
        }
        System.out.println(sum);
	}
}