import sys
input = sys.stdin.readline


mod=998244353
N,K=map(int,input().split())

DP=[0]*(N+1)
DP[0]=1
for i in range(N+1):
    DP[i]=(DP[i-1]+DP[i])%mod
    if i+K<=N:
        DP[i+K]+=DP[i]
    
print(DP[-1]%mod)