#include <bits/stdc++.h>
using namespace std;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
template <typename T>
inline T GCD(T a, T b) {
  T c;
  while (b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
template <typename T>
inline T LCM(T a, T b) {
  T c = GCD(a, b);
  a /= c;
  return a * b;
}
template <typename T>
inline T nCr(T a, T b) {
  T i, r = 1;
  for (i = 1; i <= b; i++) {
    r *= (a + 1 - i);
    r /= i;
  }
  return r;
}
template <typename T>
inline T nHr(T a, T b) {
  return nCr(a + b - 1, b);
}
template <typename T>
inline T POW(T a, T b) {
  int i, r = 1;
  for (i = 1; i <= b; i++) {
    r *= a;
  }
  return r;
}
signed main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  string s;
  cin >> s;
  int k = 0, l = 0;
  for (int i = 0; i < (s.length()); ++i) {
    if (s[i] == 'T')
      k = 0;
    else
      k++;
  }
  for (int i = s.length() - 1; i >= 0; i--) {
    if (s[i] == 'S')
      l = 0;
    else
      l++;
  }
  cout << max(k, l) * 2 << "\n";
  return 0;
}
