#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1000000007;
const int nmax = 8;
bool graph[nmax][nmax];
const int INF = 1e9;
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}
ll gcd(ll a, ll b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}
ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }
ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}
void solve(std::string X) {
  ll tmp = X.size();
  ll ans = 0;
  size_t c;
  while (X.find("ST") != string::npos) {
    X.erase(X.find("ST"), 2);
    ans += 2;
  }
  cout << tmp - ans << endl;
}
int main() {
  std::string X;
  std::cin >> X;
  solve(X);
  return 0;
}
