#include <bits/stdc++.h>
using namespace std;
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
int gcd(int x, int y) {
  if (y == 0)
    return x;
  else
    return gcd(y, x % y);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
bool is_prime(int n) {
  for (int i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return n != 1;
}
map<int, int> prime_factor(int n) {
  map<int, int> res;
  for (int i = 2; i * i <= n; i++) {
    while (n % i == 0) {
      ++res[i];
      n /= i;
    }
  }
  if (n != 1) res[n] = 1;
  return res;
}
int extgcd(int a, int b, int& x, int& y) {
  int d = a;
  if (b != 0) {
    d = extgcd(b, a % b, y, x);
    y -= (a / b) * x;
  } else {
    x = 1;
    y = 0;
  }
  return d;
}
long long mod_pow(long long x, long long n, long long mod) {
  if (n == 0) return 1;
  long long res = mod_pow(x * x % mod, n / 2, mod);
  if (n & 1) res = res * x % mod;
  return res;
}
vector<string> split(const string& str, char delim) {
  vector<string> res;
  size_t current = 0, found;
  while ((found = str.find_first_of(delim, current)) != string::npos) {
    res.push_back(string(str, current, found - current));
    current = found + 1;
  }
  res.push_back(string(str, current, str.size() - current));
  return res;
}
bool is_kadomatsu(int a, int b, int c) {
  if (a == b || a == c || b == c) return false;
  if (a > b && c > b) return true;
  if (a < b && c < b) return true;
  return false;
}
struct UF {
  int n;
  vector<int> d;
  UF() {}
  UF(int n) : n(n), d(n, -1) {}
  int root(int v) {
    if (d[v] < 0) return v;
    return d[v] = root(d[v]);
  }
  bool unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y) return false;
    if (size(x) < size(y)) swap(x, y);
    d[x] += d[y];
    d[y] = x;
    return true;
  }
  int size(int v) { return -d[root(v)]; }
};
vector<int> divisor(int n) {
  if (n == 1) return {};
  vector<int> res;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      res.emplace_back(i);
      if (i != 1 && i != n / i) res.emplace_back(n / i);
    }
  }
  return res;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  string s;
  cin >> s;
  int n = s.length();
  while (true) {
    bool flag = true;
    for (int i = (0); i < (s.length() - 1); ++i) {
      if (s[i] == 'S' && s[i + 1] == 'T') {
        flag = false;
        s.erase(i, 2);
        break;
      }
    }
    if (flag || s.length() <= 1) break;
  }
  cout << (s.length()) << endl;
  ;
  return 0;
}
