stL = list(input())

if len(stL)==1:
    print(1)
else:
    flag=1
    beforeC=""
    while flag:
        flag=0
        index=0
        while index < len(stL):
            if index==0:
                beforeC = stL[index]
            else:
                if beforeC=="S" and stL[index]=="T":
                    del stL[index-1]
                    del stL[index-1]
                    flag=1
                    break
                else:
                    beforeC = stL[index]
            index+=1
    print(len(stL))