import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int k = Integer.parseInt(sc.next());
        if(n < k) System.out.println(0);
        else System.out.println((long)Math.pow(2, n - k));
    }
}