s = input()

mod = 998244353

n = len(s)
def make_powl(b: int, nn: int):
    # b ** range(-nn, nn)
    powb = [1] * (nn * 2)
    for i in range(nn - 1):
        powb[i + 1] = powb[i] * b % mod
    invb = pow(b, mod - 2, mod)
    if invb * b % mod == 1:
        for i in range(nn):
            powb[-(i + 1)] = powb[-i] * invb % mod
    return powb
p3 = make_powl(3, n + 10)

ans = 0
mc = 0
for si in s:
    if si == "M":
        mc += 1
    else:
        ans += p3[mc]
ans %= mod
print(ans)