mod = 998244353
# nCk 用の前計算
fact = [0]*2000000
inv = [0]*2000000
fact_inv = [0]*2000000
fact[0] = 1 
fact[1] = 1
inv[1] = 1
fact_inv[0] = 1
fact_inv[1] = 1
for i in range(2,2000000):
    fact[i] = fact[i-1] * i % mod
    inv[i] = mod - inv[mod%i] * (mod//i)%mod
    fact_inv[i] = fact_inv[i-1] * inv[i]%mod
def nCk(n,k):
    return fact[n] * (fact_inv[k] * fact_inv[n - k] % mod) % mod
H, W = map(int,input().split())
if H == 1 or W == 1:
    print(1)
else:
    ans = 0
    for i in range(min(H*2-2,W*2-1)):
        ans += pow(2,(H-1)*(W-1)-i,mod) * nCk(W-1,(i+1)//2) * nCk(H-2,i//2)
        ans %= mod
    print(ans)