MOD = 998244353
H, W = map(int, input().split())

if H == 1 or W == 1:
	print(1)
	exit()

facts = [1]
inv_facts = [1]
for i in range(1, max(H - 1, W)):
    facts.append(facts[i-1] * i % MOD)
    inv_facts.append(inv_facts[i-1] * pow(i, MOD-2, MOD) % MOD)

def comb(n, r):
    return facts[n] * inv_facts[n-r] * inv_facts[r] % MOD

ans = 0
for i in range(min(2*H - 2, 2*W - 1)):
    x = (i + 1) // 2
    y = i // 2
    pow_val = pow(2, (H - 1) * (W - 1) - i, MOD)
    
    ans += pow_val * comb(W - 1, x) * comb(H - 2, y) % MOD
    ans %= MOD

print(ans)