MOD = 998244353

def main():
    import sys
    N, K = map(int, sys.stdin.readline().split())
    
    if K > N:
        print(1 % MOD)
        return
    
    max_s = N
    dp = [0] * (max_s + 2)
    sum_dp = [0] * (max_s + 2)  # sum_dp[s] stores sum from s to max_s
    
    for s in range(max_s, -1, -1):
        if s + K > N:
            dp[s] = 1
        else:
            a = s + K
            sum_val = sum_dp[a]
            dp[s] = (1 + sum_val) % MOD
        
        sum_dp[s] = (dp[s] + sum_dp[s + 1]) % MOD
    
    print(dp[0] % MOD)

if __name__ == "__main__":
    main()