#include <bits/stdc++.h>
const int inf = 0x3f3f3f3f;
using namespace std;
void fastscan(int &x) {
  bool neg = false;
  register int c;
  x = 0;
  c = getchar();
  if (c == '-') {
    neg = true;
    c = getchar();
  }
  for (; (c > 47 && c < 58); c = getchar()) x = (x << 1) + (x << 3) + c - 48;
  if (neg) x *= -1;
}
int bin1(long long int x) {
  int r = 0;
  while (x) {
    r++;
    x &= x - 1;
  }
  return r;
}
long long int exgcd(long long int a, long long int b, long long int &x,
                    long long int &y) {
  if (a == 0) {
    x = 0;
    y = 1;
    return b;
  }
  long long int x1, y1, __gcd = exgcd(b % a, a, x1, y1);
  x = y1 - (b / a) * x1;
  y = x1;
  return __gcd;
}
long long int modpow(long long int b, long long int e, long long int m) {
  long long int r = 1;
  b = b % m;
  while (e > 0) {
    if (e % 2 == 1) r = (r * b) % m;
    e /= 2;
    b = (b * b) % m;
  }
  return r;
}
long long int modinverse(long long int a, long long int mod) {
  return modpow(a, mod - 2, mod);
}
long long int modinverse2(long long int a, long long int m) {
  long long int x, y;
  exgcd(a, m, x, y);
  while (x < 0) x += m;
  return x;
}
long long int nCrmod(long long int n, long long int r, long long int m) {
  if (r > n) r = n - r;
  long long int res = 1;
  for (long long int i = r; i >= 1; i--) {
    res = (res * (n - i + 1)) % m;
    res = (res * modinverse(i, m));
  }
  return res;
}
long long int power(long long int b, long long int e) {
  if (e == 0) return 1;
  if (e % 2 == 0) return power(b * b, e / 2);
  return b * power(b * b, e / 2);
}
double powerf(double b, int e) {
  if (e == 0) return 1;
  if (e % 2 == 0)
    return powerf(b * b, e / 2);
  else {
    if (e > 0)
      return b * powerf(b * b, e / 2);
    else
      return powerf(b * b, e / 2) / b;
  }
}
long long int phi(long long int n) {
  long long int res = n, p;
  for (p = 2; p * p <= n; p++) {
    if (n % p == 0) {
      while (n % p == 0) n /= p;
      res -= res / p;
    }
  }
  if (n > 1) res -= res / n;
  return res;
}
bool isprime(long long int x) {
  if (x == 1) return false;
  for (long long int i = 2; i * i <= x; i++)
    if (x % i == 0) return false;
  return true;
}
bool prime[1000010 + 1];
void sieve() {
  long long int x, y;
  prime[0] = prime[1] = true;
  for (x = 2; x * x <= 1000010; x++) {
    if (!prime[x])
      for (y = x * x; y <= 1000010; y += x) prime[y] = true;
  }
}
bool isvowel(char c) {
  if (isupper(c)) c = tolower(c);
  return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
}
double dist(int x1, int y1, int x2, int y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
long long int stringmod(string s, long long int mod) {
  long long int res = 0;
  for (int i = 0; i < s.size(); i++) res = (res * 10 + s[i] - '0') % mod;
  return res;
}
int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};
void pre() {}
void gcj() {
  long long int t;
  cin >> t;
  for (long long int c = 1; c <= t; c++) {
    cout << "Case #" << c << ": ";
    cout << endl;
  }
}
void judge() {
  string s;
  cin >> s;
  stack<char> x;
  for (long long int i = 0; i < s.size(); i++) {
    if (s[i] == 'S')
      x.push('S');
    else if (x.top() == 'S')
      x.pop();
    else
      x.push('T');
  }
  cout << x.size();
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long int tt = 1;
  while (tt--) {
    judge();
  }
  return 0;
}
