N, K = map(int, input().split()); N -= K
if N < K:
    print(1)
    exit()
mod = 998244353
dp = [0]*(N+1); dp[0] = 1
for i in range(N+1):
    if i != 0:
        dp[i] += dp[i-1]; dp[i] %= mod
    if i + K <= N:
        dp[i+K] += dp[i]

ans = 1
for i in range(N+1):
    ans += dp[i]; ans %= mod
print(ans)