class BIT :
    def __init__(self, n) :
        self.size = n
        self.bit = [0] * (n + 1)

    def add(self, i, x) :
        while i <= self.size :
            self.bit[i] += x
            i += i & -i

    def sum(self, i) :
        s = 0
        while i > 0 :
            s += self.bit[i]
            i -= i & -i
        return s
    
    def range_sum(self, l, r) :
        return self.sum(r) - self.sum(l-1)



def main():
    
    N,K = map(int,input().split())
    if K > N:
        print(1)
        exit()
    ft = BIT(N+1)
    ft.add(0+1,1)
    mod = 998244353
    for i in range(K,N+1):
        tmp = ft.sum(i-K+1)%mod
        ft.add(i+1,tmp)
    print(ft.sum(N+1)%mod)
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    



if __name__ == '__main__':
    main()