#include <bits/stdc++.h>
using namespace std;
int int_len(int n) {
  int s = 0;
  while (n != 0) s++, n /= 10;
  return s;
}
int int_sum(int n) {
  int m = 0, s = 0, a = n;
  while (a != 0) s++, a /= 10;
  for (int i = s - 1; i >= 0; i--)
    m += n / ((int)pow(10, i)) - (n / ((int)pow(10, i + 1))) * 10;
  return m;
}
int vec_sum(vector<int> v) {
  int n = 0;
  for (int i = 0; i < v.size(); i++) n += v[i];
  return n;
}
int main() {
  int i = 0;
  string s;
  cin >> s;
  while (i < s.size() - 1 && s.size() != 0) {
    if (s[i] == 'S' && s[i + 1] == 'T') {
      s.erase(i, 2);
      i = 0;
    } else {
      i++;
    }
  }
  cout << s.size() << endl;
}
