import math

def solve():
    s = list(input())

    MOD = 998244353
    twopows = [1]
    for i in range(len(s)):
        twopows.append((twopows[-1]*2)%MOD)

    mc = 0
    ans = 0
    for i in range(len(s)):
        if s[i] == 'M':
            mc += 1
        if s[i] == 'A':
            for j in range(mc+1):
                ans += twopows[j] * math.comb(mc, j)
                ans %= MOD
    print(ans % MOD)

if __name__ == "__main__":
    solve()