#include <bits/stdc++.h>
const int MOD = 1e9 + 7;
const int iINF = 2147483647 / 2;
const long long int llINF = 9223372036854775807 / 2;
using namespace std;
using ll = long long int;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;
bool paircomp(const pair<ll, ll> &a, const pair<ll, ll> &b) {
  if (a.first == b.first) return a.second < b.second;
  return a.first < b.first;
}
ll POW(ll n, ll m) {
  if (m == 0) {
    return 1;
  } else if (m % 2 == 0) {
    ll tmp = POW(n, m / 2);
    return (tmp * tmp);
  } else {
    return (n * POW(n, m - 1));
  }
}
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  string X;
  cin >> X;
  ll count = 0;
  ll count2 = 0;
  ll ans = 0;
  for (ll i = 0; i < (X.size()); i++) {
    if (X[i] == 'S') {
      if (i > 0 && X[i - 1] != 'S') {
        ans += min(count, count2);
        count = 0;
        count2 = 0;
      }
      count++;
    } else if (count > 0 && X[i] == 'T')
      count2++;
    else {
      ans += min(count, count2);
      count = 0;
      count2 = 0;
    }
  }
  ans += min(count, count2);
  cout << X.size() - (ans * 2) << endl;
  return 0;
}
