n,k=map(int,input().split()) M=998244353 dp=[[0]*2 for _ in range(n+1)] dp[0][0]=1 for i in range(1,2*n+1): ndp=[[0]*2 for _ in range(n+1)] for j in range(n+1): if j+1<=n: if j+1==k: ndp[j+1][1]+=sum(dp[j])%M elif j+1=0: ndp[j-1][0]+=dp[j][0]%M ndp[j-1][1]+=dp[j][1]%M dp=ndp print(dp[0][1]%M)