from functools import lru_cache

mod = 998244353

@lru_cache(5 * 10**8)
def comb(n, r):
    if r > n - r:
        return comb(n, n - r)
    if r < 0:
        return 0
    
    numerator = 1
    for i in range(n - r + 1, n + 1):
        numerator *= i
        numerator %= mod
    
    denominator = 1
    for i in range(1, r + 1):
        denominator *= i
        denominator %= mod
    
    return numerator * pow(denominator, -1, mod) % mod


H, W = map(int, input().split())
if H == 1 or W == 1:
	exit(print(1))

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