#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using intpair = pair<int, int>;
using llpair = pair<ll, ll>;
using llvec = vector<ll>;
using llmat = vector<vector<ll>>;
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
ll gcd(ll a, ll b) {
  if (a == 0 || b == 0) return 0;
  if (a < b) swap(a, b);
  ll tmp = a % b;
  while (tmp != 0) {
    a = b;
    b = tmp;
    tmp = a % b;
  }
  return b;
}
ll factorial(ll x) {
  ll f = 1;
  for (ll i = 2; i < x; i++) {
    f *= i;
  }
  return f;
}
ll nPr(ll n, ll r) {
  ll result = 1;
  for (ll i = r + 1; i <= n; i++) result *= i;
  return result;
}
ll nCr(ll n, ll r) {
  if (n == r) {
    return 1;
  }
  if (r > n) {
    return 0;
  }
  if (r > n / 2) {
    r = n - r;
  }
  if (n == 0) {
    return 0;
  }
  if (r == 0) {
    return 1;
  }
  if (r == 1) {
    return n;
  }
  double result = 1;
  for (double i = 1; i <= r; i++) {
    result *= (n - i + 1) / i;
  }
  return (ll)result;
}
ll GreaterBinarySearch(ll* array, ll key, ll max, ll min) {
  if (array[max] < array[min]) {
    return NULL;
  } else {
    ll mid = max + (min - max) / 2;
    if (array[mid] < key) {
      return GreaterBinarySearch(array, key, max, mid - 1);
    }
    if (array[mid] > key) {
      return GreaterBinarySearch(array, key, mid + 1, min);
    } else {
      return mid;
    }
  }
}
int DigitNum(ll n) {
  int digit = 0;
  ll wari = 1LL;
  while (n / wari) {
    digit++;
    wari *= 10;
  }
  return digit;
}
bool IsPrime(ll num) {
  if (num < 2)
    return false;
  else if (num == 2)
    return true;
  else if (num % 2 == 0)
    return false;
  double sqrtNum = sqrt(num);
  for (ll i = 3; i <= sqrtNum; i += 2) {
    if (num % i == 0) {
      return false;
    }
  }
  return true;
}
vector<ll> Divisor(ll x) {
  vector<ll> result;
  ll i = 1LL;
  for (; i * i < x; i++) {
    if (x % i) continue;
    result.push_back(i);
    result.push_back(x / i);
  }
  if (i * i == x && x % i == 0) result.push_back(i);
  sort(result.begin(), result.end());
  return result;
}
vector<llpair> PrimeFact(ll x) {
  vector<llpair> result;
  ll ex = 0LL;
  if (x % 2 == 0) {
    while (x % 2 == 0) {
      x /= 2;
      ex++;
    }
    result.push_back({2, ex});
  }
  for (ll i = 3LL; i * i <= x; i += 2) {
    if (x % i) continue;
    ex = 0LL;
    while (x % i == 0) {
      x /= i;
      ex++;
    }
    result.push_back({i, ex});
  }
  if (x != 1) result.push_back({x, 1});
  return result;
}
bool Palind(string s) { return s == string(s.rbegin(), s.rend()); }
int main() {
  string S;
  cin >> S;
  int N = S.length();
  int LT = 0, RS = 0;
  for (int i = 0; S[i] == 'T'; i++) LT++;
  for (int i = N - 1; S[i] == 'S'; i--) RS++;
  cout << max(LT, RS) * 2 << endl;
}
