24 соседние различные

#https://inf-ege.sdamgia.ru/problem?id=27421
s = open('24_demo (1).txt').readline()
l = 0
r = 0
answ = 1
while r < len(s):
    if r + 1 < len(s) and s[r] != s[r + 1]:
        r += 1
        answ = max(answ, r - l + 1)
    else:
        r += 1
        l = r
print(answ)