n,K=map(int,input().split())
M=998244353

def f(k):
  q=[0]*(k+1)
  q[0]=1
  for i in range(2*n):
    nq=[0]*(k+1)
    for j in range(k+1):
      if j+1<=k:
        nq[j+1]+=q[j]
        nq[j+1]%=M
      if j-1>=0:
        nq[j-1]+=q[j]
        nq[j-1]%=M
    q=nq
  return q[0]

print((f(K)-f(K-1))%M)