#include <bits/stdc++.h>
using namespace std;
const int dy[] = {0, 1, 0, -1};
const int dx[] = {1, 0, -1, 0};
using LL = long long int;
using LD = long double;
const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;
using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  string x;
  cin >> x;
  string kx;
  stack<int> st;
  for (decltype(200030) i = 0; i < (200030); i++) {
    if (kx == x) break;
    if (x.empty()) break;
    kx = x;
    for (decltype(x.size() - 1) i = 0; i < (x.size() - 1); i++) {
      if (x[i] == 'S' && x[i + 1] == 'T') {
        st.push(i);
      }
    }
    while (!st.empty()) {
      int pos = st.top();
      st.pop();
      x.erase(pos, 2);
    }
  }
  cout << x.size() << "\n";
  return 0;
}
