N,K = map(int,input().split())
dp = [0] * (N + 2)
ans = 0
P = 998244353
dp[0] = 1
sub = [0] * (N + 2)
for i in range(N + 1):
	dp[i] += dub[i]
	dp[i] %= P
	ans += dp[i]
	ans %= P
	if i + K <= N:
		sub[i + K] += dp[i]
		sub[i + K] %= P
	sub[i + 1] += sub[i]
	sub[i + 1] %= P
print(ans)