/* imports all std modules {{{*/
import
  std.algorithm,
  std.array,
  std.ascii,
  std.base64,
  std.bigint,
  std.bitmanip,
  std.compiler,
  std.complex,
  std.concurrency,
  std.container,
  std.conv,
  std.csv,
  std.datetime,
  std.demangle,
  std.encoding,
  std.exception,
  std.file,
  std.format,
  std.functional,
  std.getopt,
  std.json,
  std.math,
  std.mathspecial,
  std.meta,
  std.mmfile,
  std.net.curl,
  std.net.isemail,
  std.numeric,
  std.parallelism,
  std.path,
  std.process,
  std.random,
  std.range,
  std.regex,
  std.signals,
  std.socket,
  std.stdint,
  std.stdio,
  std.string,
  std.system,
  std.traits,
  std.typecons,
  std.uni,
  std.uri,
  std.utf,
  std.uuid,
  std.variant,
  std.zip,
  std.zlib;
/*}}}*/
/* libnum {{{*/
void amax(N, Args...)(ref N x, Args y) {
  x = x.max(y);
}
void amin(N, Args...)(ref N x, Args y) {
  x = x.min(y);
}
auto maxE(R)(R r) if (isInputRange!R) {
  ElementType!R x = r.front;
  r.popFront();
  foreach (y; r) x.amax(y);
  return x;
}
auto minE(R)(R r) if (isInputRange!R) {
  ElementType!R x = r.front;
  r.popFront();
  foreach (y; r) x.amin(y);
  return x;
}
/*}}}*/


/+---test
TSTTSS
---+/
/+---test
SSTTST
---+/
/+---test
TSSTTTSS
---+/

void main(string[] args) {
  const S = readln.chomp;

  const l = S.countUntil!(c => c != 'T');
  const r = S.retro.countUntil!(c => c != 'S');

  long ans = l + r, dep;
  foreach (c; S[l..$-r]) {
    if (c == 'S') {
      ++dep;
      dep.amax(1);
    } else if (c == 'T' && dep > 0) {
      --dep;
    } else {
      ++ans;
    }
  }
  ans.writeln;
}
