#include <bits/stdc++.h>
using namespace std ;

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) begin(r),end(r)
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)
#define vvl(v,w,h,init) vector<vector<ll>> v(w,vector<ll>(h,init))
#define mp(a,b) make_pair(a,b)

#define rep(i,n) for(int i = 0; i < (int)(n);++i)
#define REP(i,a,b) for(int i = (a);i < (int)(b);++i)
#define repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

using ll = long long;
using pii = pair<int,int> ;
using pll = pair<ll,ll> ;

const ll mod = 1e9+7;
constexpr ll inf = ((1<<30)-1)*2+1 ;
constexpr double PI = acos(-1.0) ;
double eps = 1e-10 ;
const int dy[] = {-1,0,1,0,1,-1,1,-1};
const int dx[] = {0,-1,0,1,1,-1,-1,1};
ll FindErase(string &v,char tar){
  ll cnt = 0;
  for(auto it = v.begin(); it != v.end();){
    if((*it) == tar){
      it = v.erase(it);
      ++cnt;
    }
    else{
      ++it;
    }
  }
  return cnt;
}


ll FindErase(string &v,string tar){
  bool f = true;
  while(f){
    f = false;
    rep(i,v.size()-1){
      if(v[i] == 'S' && v[i+1] == 'T'){
        v[i] = ' '; 
        v[i+1] = ' '; 
        f = true;
      }
    } 
    FindErase(v,' ');
  }
  return v.size();
}
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  string s;
  cin >> s;
  std::cout << FindErase(s,"ST") << std::endl;
  return 0;
}
