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