пути

summ = 0
A = []


def kekus(pr, st):
    global A
    global summ
    if pr == lenushka:
        if st == "L":
            summ += 1
        return summ
    if A[pr] == "B":
        summ += 1
        return kekus(pr + 1, st)
    if A[pr] == "L" and st == "L":
        if kekus(pr + 1, "R") < kekus(pr + 1, "L"):
            summ += 1
            return kekus(pr + 1, "R")
        else:
            summ += 1
            return kekus(pr + 1, "L")
    if A[pr] == "R" and st == "R":
        if kekus(pr + 1, "R") > kekus (pr + 1, "L"):
            summ += 1
            return kekus(pr + 1, "L")
        else:
            summ += 1
            return kekus(pr + 1, "R")
    return kekus(pr + 1, st)


lenushka = 0
a = input()
st = "L"
lenushka = len(a)
for i in range(len(a)):
    A.append(a[i])

print(kekus(0, st))