M=998244353
N=10**6
fa=[1]
for i in range(1,N+1):
  fa+=[fa[-1]*i%M]
fb=[pow(fa[N],M-2,M)]
for i in reversed(range(1,N+1)):
  fb+=[fb[-1]*i%M]
fb.reverse()
fc=lambda n,k:fa[n]*fb[k]*fb[n-k]%M if n>=k>=0 else 0
a,b=map(int,input().split())
print(fc(a-1+b-1,a-1))