mod = 998244353
N,K = map(int,input().split())
dp = [0]*(N+3)
dp[0] = 1
dp[1] = -1
for i in range(N+2):
    if i != 0:
        dp[i] += dp[i-1]
        dp[i] %= mod

    if i+K <= N:
        dp[i+K] += dp[i]
        dp[i+K] %= mod

        dp[N+1] -= dp[i]
        dp[N+1] %= mod

print(sum(dp)%mod)
#print(dp)