#include <bits/stdc++.h>
#include <atcoder/all>
#include <iostream>
#include <cmath>
using namespace std;
using namespace atcoder;
using ll = long long;
using lb = long double;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vll = vector<ll>;
using vb = vector<bool>;
using vvll = vector<vector<ll>>;
using vP = vector<P>;
using Graph = vector<vector<ll>>;
using WGraph = vector<vector<pair<ll, ll>>>; // コスト、頂点番号の順
using mint = modint998244353;
//using mint = long double;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
mt19937_64 rng(58);
long double PI = 3.14159265358979;
const ll LLMAX = 9223372036854775807;
const ll INF = 1e18;
vector<ll> di = {-1, 0, 1, 0}; // 上左下右
vector<ll> dj = {0, -1, 0, 1};
template<typename T> inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false)); }
template<typename T> inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false)); }

int main() {
    string s;
    cin >> s;

    ll n = s.size();
    vector<mint> bino(n + 1);
    bino[0] = 1;
    mint p = 1 + 2;
    rep (i, n) bino[i + 1] = bino[i] * p;

    mint ans = 0;
    ll cntM = 0;
    rep (i, n) {
        if (s[i] == 'M') cntM++;
        else {
            ans += bino[cntM];
        }
    }

    cout << ans.val() << endl;
    return 0;
}