import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int K = scan.nextInt();
		scan.close();
		int ans;
		if(K == 1) {
			ans = (int)Math.pow(2, N - K) - N;
		}else {
			ans = (int)Math.pow(2, N - K);
		}
		System.out.println(ans);
	}
}