import sys

input_methods=['clipboard','file','key']
using_method=1
input_method=input_methods[using_method]

tin=lambda : map(int, input().split())
lin=lambda : list(IN())
mod=1000000007

#+++++

def main():
	#a = int(input())
	#b , c = tin()
	s = list(input())[:-1]

	p=''
	pi=-1
	is_exist_st=False
	#pa(s)
	for i, c in enumerate(s):
		if p == 'S' and c == 'T':
			s[pi] = 'e'
			s[i] = 'e'
			#print(s)
			is_exist_st = True
			p=''
			for bj in range(i):
				if s[i-1-bj]!='e':
					p=s[i-1-bj]
					pi=i-1-bj
					break
		else:
			p=c
			pi=i
	return len(s)-s.count('e')
	
	
#+++++
isTest=False

def pa(v):
	if isTest:
		print(v)
		
def input_clipboard():
	import clipboard
	input_text=clipboard.get()
	input_l=input_text.splitlines()
	for l in input_l:
		yield l

if __name__ == "__main__":
	if sys.platform =='ios':
		if input_method==input_methods[0]:
			ic=input_clipboard()
			input = lambda : ic.__next__()
		elif input_method==input_methods[1]:
			sys.stdin=open('inputFile.txt')
		else:
			pass
		isTest=True
	else:
		pass
		input = sys.stdin.readline
			
	ret = main()
	if ret is not None:
		print(ret)