N,K = map(int,input().split())
dp = [0] * (N + 1)
dp[0] = 1
S = [0] * (N + 1)
S[0] = 1
DIV = 998244353

for i in range(1, N + 1):
    if i - K < 0:
        dp[i] = 0
    else:
        dp[i] += S[i - K]
        dp[i] %= DIV
    S[i] += S[i - 1] + dp[i]
    S[i] %= DIV

print(S[-1])