#include <bits/stdc++.h>
using namespace std;
const int inf = numeric_limits<int>::max() / 4;
const long long linf = numeric_limits<long long>::max() / 4;
const unsigned long long ulinf = numeric_limits<unsigned long long>::max() / 4;
const double pi = acos(-1);
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
const int dx8[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
const int dy8[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
long long modpow(long long i, long long j) {
  long long tmp = 1;
  while (j) {
    if (j % 2) tmp = ((tmp * i) % (long long)(1e9 + 7));
    i = ((i * i) % (long long)(1e9 + 7));
    j /= 2;
  }
  return tmp;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
vector<string> split(const string &str, char sep) {
  vector<string> v;
  stringstream ss(str);
  string buffer;
  while (getline(ss, buffer, sep)) {
    v.push_back(buffer);
  }
  return v;
}
int main() {
  string s;
  cin >> s;
  while (1) {
    int index = s.find("ST");
    if (index == -1) break;
    s = s.erase(index, 2);
  }
  cout << (((int)(s).size())) << endl;
  return 0;
}
