use proconio::{input, marker::Chars};

fn main() {
    input! {
        s: Chars,
    }

    let mut ans = 0;

    let mut cnt_m = 0;
    for c in s {
        if c == 'M' {
            cnt_m += 1;
        }
        else {
            let val = mod_pow(3, cnt_m);
            ans = mod_add(ans, val);
        }
    }
    println!("{}", ans);
}

const MOD : usize = 998244353;
#[allow(unused)]
fn mod_add(a: usize, b: usize) -> usize { let a = a % MOD; let b = b % MOD; (a + b) % MOD }
#[allow(unused)]
fn mod_sub(a: usize, b: usize) -> usize { let a = a % MOD; let b = b % MOD; (a + MOD - b) % MOD }
#[allow(unused)]
fn mod_mul(a: usize, b: usize) -> usize { let a = a % MOD; let b = b % MOD; (a * b) % MOD }
#[allow(unused)]
fn mod_div(a: usize, b: usize) -> usize { mod_mul(a, mod_pow(b, MOD-2)) }
#[allow(unused)]
fn mod_pow(mut a: usize, mut b: usize) -> usize {
    let mut ret = 1;
    while b > 0 {
        if b % 2 == 1 { ret = mod_mul(ret, a); }
        a = mod_mul(a, a);
        b /= 2;
    }
    ret
}