from atcoder.lazysegtree import LazySegTree
N, K = map(int, input().split()); N -= K
mod = 998244353
def op(a, b):
    return (a+b)%mod
def mapping(f, g):
    return (f+g)%mod
def composition(f, g):
    return (f+g)%mod
lst = LazySegTree(op, 0, mapping, composition, 0, [1]*(N+1))
for i in range(N):
    if i + K <= N:
        lst.apply(i+K, N+1, lst.get(i))
print(lst.all_prod()+1)