static void Main()
{
var ss = new StreamScanner(new StreamReader(Console.OpenStandardInput()));
var sw = new StreamWriter(Console.OpenStandardOutput())
{
AutoFlush = false
};
new Program().Solve(ss, sw);
sw.Flush();
}
void Solve(StreamScanner ss, StreamWriter sw)
{
//---------------------------------
var ls = new Stack <char>();
var rs = new Stack <char>(Console.ReadLine().Reverse());
while (rs.Count > 0)
{
if (ls.Count != 0 && ls.Peek() == 'S' && rs.Peek() == 'T')
{
ls.Pop();
rs.Pop();
}
else
{
ls.Push(rs.Pop());
}
}
sw.WriteLine(ls.Count);
//---------------------------------
}