#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using mint = atcoder::modint998244353;

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

    int mc = 0;
    mint ans = 0;
    for (char c : S){
        if (c == 'M') mc++;
        else ans += mint(3).pow(mc);
    }

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