#include <bits/stdc++.h>
using namespace std;
int main() {
  string x;
  cin >> x;
  int num = 10000;
  while (num--) {
    if (x.size() >= 2) {
      bool ok = false;
      for (int i = 0; i + 1 < x.size(); i++) {
        if (x[i] == 'S' && x[i + 1] == 'T') ok = true;
        x.erase(i, 2);
        break;
      }
      if (ok == false) {
        printf("%d\n", x.size());
        return 0;
      }
    } else {
      printf("%d\n", x.size());
      return 0;
    }
  }
}
