mod = 998244353
class Dual_Fenwick_Tree:
    def __init__(self, n):
        self._n = n + 1
        self.data = [0] * (n + 1)

    def _add(self, p, x):
        assert 0 <= p < self._n
        p += 1
        while p <= self._n:
            self.data[p - 1] += x
            self.data[p - 1] %= mod
            p += p & -p

    def sum(self, l, r):
        assert 0 <= l <= r <= self._n
        return (self._sum(r) - self._sum(l)) % mod

    def _sum(self, r):
        s = 0
        while r > 0:
            s += self.data[r - 1]
            s %= mod
            r -= r & -r
        return s

    # A[l:r]にvを足す
    def add(self, l, r, v):
        self._add(l, v)
        self._add(r, -v)
    # A[x]を返す
    def get(self, x):
        return self.sum(0, x + 1) % mod

    def __str__(self):
        temp = []
        for i in range(self._n):
            temp.append(str(self.sum(0, i + 1)))
        return ' '.join(temp)


N, K = map(int, input().split())   
T = Dual_Fenwick_Tree(N + 1)
T.add(0, 1, 1)
ans = 0
for i in range(N):
    v = T.get(i)
    if i + K >= N + 1:
        break
    T.add(i + K, N + 1, v)

for i in range(N + 1):
    ans += T.get(i)
    ans %= mod
print(ans % mod)