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

using ll = long long;
[[maybe_unused]] constexpr ll INF = (1LL << 60) - 1;
using mint = modint998244353;

void solve() {
    string s;
    cin >> s;
    ll n = s.size();
    ll cnt = 0;
    mint ans = 0;
    for (ll i = 0; i < n; ++i) {
        if (s[i] == 'M') {
            ++cnt;
            continue;
        }
        ans += (mint(3)).pow(cnt);
    }
    cout << ans.val() << "\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}