## https://yukicoder.me/problems/no/3458

MOD = 998244353

def main():
    S = input()

    m_number = 0
    answer = 0
    for s in S:
        if s == "M":
            m_number += 1
        elif s == "A":
            answer += pow(3, m_number, MOD)
            answer %= MOD
    print(answer)










                




if __name__ == "__main__":
    main()