h,w=map(int,input().split())
M=998244353
fa=[1,1]
fb=[1,1]
for i in range(2,h+w+1):
  fa+=[fa[-1]*i%M]
  fb+=[fb[-1]*(M//i)*fb[M%i]*fa[M%i-1]*(-1)%M]
ans=0
for i in range(1,min(h-1,w-1)+1):
  ans+=pow(2,h*w-(h+w-1)-(2*i-1),M)*fa[h-1-1]*fb[i-1]*fb[h-1-1-(i-1)]*fa[w-1]*fb[i]*fb[w-1-i]
  ans%=M
for i in range(1,min(h-1,w)+1):
  ans+=pow(2,h*w-(h+w-1)-(2*i-2),M)*fa[h-1-1]*fb[i-1]*fb[h-1-1-(i-1)]*fa[w-1]*fb[i-1]*fb[w-1-(i-1)]
  ans%=M
print(ans)