MOD = 998244353

N, K = map(int, input().split())
ans = [1]*(N+1)
acc = [0]*(N+2)

for i in range(N, -1, -1):
	ans[i] += acc[min(N+1, i+K)]
	ans[i] %= MOD
	acc[i] = ans[i] + acc[i+1]
	acc[i] %= MOD

print(ans[0])