import java.math.BigInteger;
import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);		
		int N = s.nextInt(), K = s.nextInt();
		
		BigInteger[] dp = new BigInteger[N+1];
		dp[0] = new BigInteger("1");
		for(int j = 1; j <= N; j++)
			dp[j] = new BigInteger("0");
		
		for(int i = 1; i <= K; i++){
			for(int j = 1; j <= N; j++){
				if(j>=i){
					dp[j] = dp[j].add(dp[j-i]);
				}
//				System.out.print(dp[j]+" ");
			}
//			System.out.println();
		}
		System.out.println(dp[N]);
	}

}