#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
template<typename T>bool chmax(T &x, T y){if(x>=y)return false;x=y;return true;}
template<typename T>bool chmin(T &x, T y){if(x<=y)return false;x=y;return true;}
const long long mod = 998244353;

long long modpow(long long n, long long r){
  long long ans = 1;
  while(r){
    if(r%2)ans = ans * n % mod;
    n = n * n % mod;
    r /= 2;
  }
  return ans;
}

int main(){
  long long ans = 0, c = 0;
  string S;
  cin >> S;
  for(auto x: S){
    if(x=='M')c++;
    else ans = (ans+modpow(3, c))%mod;
  }
  cout << ans << endl;
}