#include <atcoder/modint>
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using mint = atcoder::modint998244353;

int main() {
    string s;
    cin >> s;
    mint ans = 0;
    mint x = 1;
    for (char c : s) {
        if (c == 'M')
            x *= 3;
        else
            ans += x;
    }
    cout << ans.val() << endl;
}