## https://yukicoder.me/problems/no/1552

MOD = 998244353

def my_pow(a, x):
    if a == 0:
        return 0
    else:
        return pow(a, x, MOD)

def linear_sum(N):
    ans = (N * (N + 1)) % MOD
    ans *= pow(2, MOD - 2, MOD)
    ans %= MOD
    return ans

def main():
    N, M = map(int, input().split())

    # 最小値から考える
    answer_min = 0
    max_linear_sum = linear_sum(M)
    for m in range(1, M + 1):
        min_linear_sum = linear_sum(m - 1)
        diff_linear_sum = (max_linear_sum - min_linear_sum) % MOD

        m0 = M - m + 1
        m0 = my_pow(m0, N - 1)
        m0 *= N
        m0 %= MOD
        a = (diff_linear_sum * m0) % MOD

        min_linear_sum2 = linear_sum(m)
        diff_linear_sum2 = (max_linear_sum - min_linear_sum2) % MOD
        b = my_pow(diff_linear_sum2, N)

        m0 = M - m
        m0 = my_pow(m0, N - 1)
        m0 *= N
        m0 %= MOD
        b = (diff_linear_sum2 * m0) % MOD

        c = (a - b) % MOD
        ans = (c * m) % MOD
        answer_min += ans
        answer_min %= MOD

    # 最大値
    answer_max = 0
    for m in range(1, M + 1):
        max_linear_sum = linear_sum(m)
        m0 = m
        m0 = my_pow(m0, N - 1)
        m0 *= N
        m0 %= MOD
        a = (max_linear_sum * m0) % MOD

        max_linear_sum2 = linear_sum(m - 1)
        m0 = m - 1
        m0 = my_pow(m0, N - 1)
        m0 *= N
        m0 %= MOD
        b = (max_linear_sum2 * m0) % MOD

        c = (a - b) % MOD
        ans = (c * m) % MOD
        answer_max += ans
        answer_max %= MOD
    answer = (answer_max - answer_min) % MOD
    print(answer)


        




if __name__ == "__main__":
    main()