#![allow(non_snake_case)]
#![allow(dead_code, unused_macros)]

use std::collections::HashMap;
use std::hash::Hash;
#[allow(unused_imports)]
use proconio::{input, marker::Usize1, marker::Chars};
#[allow(unused_imports)]
use itertools::Itertools;

macro_rules! d {
    ( $( $x:expr ),* $(,)? ) => {
        println!(
            concat!( $( stringify!($x), "={:?} " ),* ),
            $( $x ),*
        );
    };
}

fn mod_pow(base: i64, exp: i64, modulus: i64) -> i64 {
    if exp == 0 { return 1 }
    if exp == 1 { return base % modulus }
    let x = mod_pow(base, exp / 2, modulus);
    if exp & 1 > 0 {
        ((x * base) % modulus) * x % modulus
    } else {
        x * x % modulus
    }
}

const MOD: i64 = 998244353;

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

    let mut ans = 0;
    let mut m = 0;
    for c in S {
        if c == 'A' {
            ans += mod_pow(3, m, MOD);
            ans %= MOD;
        } else if c == 'M' {
            m += 1;
        }
    }

    println!("{ans}");
}