class fenwick_tree():
    n=1
    data=[0 for i in range(n)]
    def __init__(self,N):
        self.n=N
        self.data=[0 for i in range(N)]
    def add(self,p,x):
        assert 0<=p<self.n,"0<=p<n,p={0},n={1}".format(p,self.n)
        p+=1
        while(p<=self.n):
            self.data[p-1]+=x
            p+=p& -p
    def sum(self,l,r):
        assert (0<=l and l<=r and r<=self.n),"0<=l<=r<=n,l={0},r={1},n={2}".format(l,r,self.n)
        return self.sum0(r)-self.sum0(l)
    def sum0(self,r):
        s=0
        while(r>0):
            s+=self.data[r-1]
            r-=r&-r
        return s

N,K=map(int,input().split())
MOD = 998244353
BIT = fenwick_tree(N+1)
BIT.add(0, 1)
for i in range(1, N+1):
  kiyo = BIT.sum0(i-K+1)
  BIT.add(i, kiyo)
  value = BIT.sum(i, i+1)
  BIT.add(i, -value)
  BIT.add(i, value % MOD)

print(BIT.sum(0, N+1)%MOD)