n,k=map(int,input().split())

dp=[0 for _ in range(n+1)]
dp[0]=1
dp[1]=-1

mod=998244353

for i in range(n):
  if i+k<=n:
    dp[i+k]+=dp[i]
    dp[i+k]%=mod
  dp[i+1]+=dp[i]
  dp[i+1]%=mod
#print(dp)

ans=0
for i in range(n+1):
  ans+=dp[i]
  ans%=mod
print(ans)