S = input()
init_count = len(S)

tmp_i = 0
while len(S) > 1:
    no_01 = True
    before_s = None
    for i, s in enumerate(S[tmp_i:]):
        if i == 0:
            before_s = s
            continue
        if before_s != s:
            no_01 = False
            print(S[:tmp_i + i-1], '(', S[tmp_i + i - 1], ' | ', S[tmp_i + i],  ')', S[tmp_i + i+1:])
            newS = S[:tmp_i + i-1] + S[tmp_i + i+1:]
            S = newS
            print('newS: ', newS)
            tmp_i = tmp_i + i - 2
            if tmp_i < 0:
                tmp_i = 0
            print(tmp_i)
            break
    if no_01:
        break
print(init_count - len(S))