#include <bits/stdc++.h>
using namespace std;
struct Fast {
  Fast() {
    std::cin.tie(0);
    ios::sync_with_stdio(false);
    cout.precision(20);
  }
} fast;
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vii = vector<vector<int>>;
using vl = vector<long long>;
using vll = vector<vector<long long>>;
using pi = pair<int, int>;
using pl = pair<long long, long long>;
template <typename T>
using PQ = priority_queue<T>;
template <typename T>
using minPQ = priority_queue<T, vector<T>, greater<T>>;
const long long dx[] = {1, 0, -1, 0};
const long long dy[] = {0, 1, 0, -1};
const long long dx8[] = {1, 1, 0, -1, -1, -1, 0, 1};
const long long dy8[] = {0, 1, 1, 1, 0, -1, -1, -1};
const long long dx9[] = {1, 1, 0, -1, -1, -1, 0, 1, 0};
const long long dy9[] = {0, 1, 1, 1, 0, -1, -1, -1, 0};
const int INF = 1000000007;
const long long LINF = 1000000000000000007;
template <typename T>
inline bool chmin(T& a, const T& b) {
  if (a > b) a = b;
  return a > b;
}
template <typename T>
inline bool chmax(T& a, const T& b) {
  if (a < b) a = b;
  return a < b;
}
long long max(long long x, int y) { return max(x, (long long)y); }
long long max(int x, long long y) { return max((long long)x, y); }
long long min(long long x, int y) { return min(x, (long long)y); }
long long min(int x, long long y) { return min((long long)x, y); }
signed main() {
  string X;
  cin >> X;
  int N = X.size();
  int t = 0;
  int s = 0;
  for (long long(i) = (0); (i) < (N); (i)++) {
    if (X[i] != 'T') break;
    t++;
  }
  for (long long(i) = (N)-1; (i) >= (0); (i)--) {
    if (X[i] != 'S') break;
    s++;
  }
  cout << 2 * max(s, t) << endl;
}
