def main():
    N,K = map(int,input().split())
    mod = 998244353
    dp = [0 for _ in range(N+1)]
    dp[0] = 1
    acum = []
    for i in range(min(K,N+1)):
        acum.append(1)
    for i in range(K,N+1):
        dp[i] += acum[i-K]
        dp[i] = dp[i] % mod
        acum.append(acum[-1]+dp[i])
    print(sum(dp)%mod)
    
    
    
    


if __name__ == '__main__':
    main()