#input of int(split by space)
def get_i()
  return gets.chomp.split(" ").map(&:to_i)
end
#input of float(split by space)
def get_f()
  return gets.chomp.split(" ").map(&:to_f)
end
#input of string(split by space)
def get()
  return gets.chomp.split(" ")
end
#input of string(split per one character)
def get_nsp()
  return gets.chomp.split("")
end
#yes or no decision
def yn_judge(bool,y="Yes",n="No")
  return bool ? y : n 
end
#create of array
def array(size1,init=nil,size2=-1)
  if size2==-1
      return Array.new(size1){init}
  else
      return Array.new(size2){Array.new(size1){init}}
  end
end

def max(a,b)
    return a>b ? a : b
end

def min(a,b)
    return a>b ? b : a
end

INF=Float::INFINITY

X=get_nsp
N=X.size
ans=0
l=0
r=N-1
N.times do|i|
    if X[i]=="T"
        ans+=1
    else
        l=i
        break
    end
end
N.times do|i|
    if X[N-1-i]=="S"
        ans+=1
    else
        r=N-1-i
        break
    end
end
unless l<=r
    puts N
    exit
end
x=X[l..r]
n=x.size
s_cnt=x.count("S")
t_cnt=n-s_cnt
puts ans+(s_cnt-t_cnt).abs