#include <bits/stdc++.h>                                                                       
                                                                                               
using namespace std;                                                                           
                                                                                               
#define all(x) x.begin(), x.end()                                                              
#define rep(i, n) for (int i = 0; i < n; ++i)                                                  
#define reps(i, m, n) for (int i = m; i <= n; ++i)                                             
                                                                                               
using i64 = long long;                                                                         
using pii = pair<i64, i64>;                                                                    
                                                                                               
template<class A, class B>inline bool chmax(A &a, const B &b){return b > a ? a = b,1 : 0;}     
template<class A, class B>inline bool chmin(A &a, const B &b){return b < a ? a = b,1 : 0;}     
                                                                                               
constexpr int INF = 0x3f3f3f3f;                                                                
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;                                                     
constexpr int MOD = int(1e9) + 7;                                                              
                                                                                               
signed main()                                                                                  
{                                                                                              
  ios::sync_with_stdio(false);                                                                 
  cin.tie(nullptr);                                                                            
                                                                                               
  string x;                                                                                    
  cin >> x;                                                                                    
                                                                                               
  stack<char> st;                                                                              
  for (auto e : x) {                                                                           
    if (e == 'S') st.push(e);                                                                  
    else if ((e == 'T' && st.empty()) || (e == 'T' && st.top() == 'T')) st.push(e);            
    else if (e == 'T' && st.top() == 'S') st.pop();                                            
  }                                                                                            
                                                                                               
  cout << st.size() << "\n";                                                                   
                                                                                               
  return 0;                                                                                    
}                                                                                              

Measured memory_bytes: 720