mod = 998244353
n = 10**6
fact = [1 for i in range(n+1)]
fact_inv = [1 for i in range(n+1)]
for i in range(1,n+1):
  fact[i] = fact[i-1]*i % mod
fact_inv[-1] = pow(fact[-1],mod-2,mod)
for i in range(n,0,-1):
  fact_inv[i-1] = fact_inv[i]*i % mod
def binom(n,r):
  if n < r or n < 0 or r < 0:
    return 0
  res = fact_inv[n-r] * fact_inv[r] % mod
  res *= fact[n]
  res %= mod
  return res

H,W = map(int,input().split())
if min(H,W) == 1:
  print(1)
  exit()
ans = 0
for c in range(2,H+W+1):
    h,w = (c + 1) // 2,c // 2
    res = binom(H-2,h-1) * binom(W-2,w-1) % mod
    res = res * pow(2,(H*W - (H + W - 1 + c - 1)) % (mod - 1),mod) % mod
    ans = (ans + res) % mod

    w,h = (c + 1) // 2,c // 2
    res = binom(H-2,h-1) * binom(W-2,w-1) % mod
    res = res * pow(2,(H*W - (H + W - 1 + c - 2)) % (mod - 1),mod) % mod
    ans = (ans + res) % mod

print(ans)