N,K=map(int,input().split())
u=[1]*(N+1)
mod=998244353
for i in range(1,N+1):
  u[i]=u[i-1]*i
  u[i]%=mod
u2=[1]*(N+1)
for i in range(N+1):
  u2[i]=pow(u[i],-1,mod)
def ncm(x,y):
  ans=u[x]*u2[y]
  ans%=mod
  ans*=u2[x-y]
  ans%=mod
  return ans
result=1
for k in range(1,N+1):
  rest=N-k*K
  if rest<0:
    break
  result+=ncm(rest+k,k)
  result%=mod
print(result)