MOD = 998244353

N, M = map(int, input().split())

if M == 0:
    print(0)
else:
    max_n = M + 1
    fact = [1] * (max_n + 1)
    for i in range(1, max_n + 1):
        fact[i] = fact[i-1] * i % MOD
    
    inv_fact = [1] * (max_n + 1)
    inv_fact[max_n] = pow(fact[max_n], MOD-2, MOD)
    for i in range(max_n - 1, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(n, k):
        if k < 0 or k > n:
            return 0
        return fact[n] * inv_fact[k] % MOD * inv_fact[n - k] % MOD
    
    total = 0
    # s=0 term
    term = M * pow(2 * M, N, MOD) % MOD
    total = (total + term) % MOD
    
    for s in range(1, M + 1):
        k = s + 1
        c = comb(M + 1, k)
        val = (2 * M - s) % MOD
        pow_val = pow(val, N, MOD)
        term = c * pow_val % MOD
        if s % 2 == 1:
            term = (-term) % MOD
        total = (total + term) % MOD
    
    print(total % MOD)