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