n,k=map(int,input().split()) M=998244353 dp=[[[0]*3 for _ in range(n+1)]for _ in range(2*n+1)] dp[0][0][0]=1 for i in range(1,2*n+1): for j in range(n+1): if j+1<=n: if j+1==k: dp[i][j+1][1]+=sum(dp[i-1][j][:2])%M elif j+1>k: dp[i][j+1][2]+=sum(dp[i-1][j])%M else: dp[i][j+1][0]+=dp[i-1][j][0]%M dp[i][j+1][1]+=dp[i-1][j][1]%M dp[i][j+1][2]+=dp[i-1][j][2]%M if j-1>=0: dp[i][j-1][0]+=dp[i-1][j][0]%M dp[i][j-1][1]+=dp[i-1][j][1]%M dp[i][j-1][2]+=dp[i-1][j][2]%M print(dp[-1][0][1]%M)