import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {
	
	public static long dfs(long[][] memo, final int N, final int bit, final int K){
		if(memo[bit][K] >= 0){
			return memo[bit][K];
		}
		
		boolean has_lower = false;
		for(int k = 1; k < K; k++){
			if((bit & (1 << k)) == 0){
				has_lower = true;
				break;
			}
		}
		
		if(!has_lower){
			return memo[bit][K] = 0;
		}
		
		memo[bit][K] = 1;
		for(int k = K + 1; k <= N; k++){
			if((bit & (1 << k)) != 0){ continue; }
			
			memo[bit][K] += dfs(memo, N, bit | (1 << k), k);
		}
		
		return memo[bit][K];
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		final int K = sc.nextInt();
		
		long[][] memo = new long[1 << (N + 1)][N + 1];
		for(int i = 0; i < 1 << (N + 1); i++){
			Arrays.fill(memo[i], -1);
		}
		
		System.out.println(dfs(memo, N, 1 << K, K));
	}

}