24 отрезок только из X

#https://inf-ege.sdamgia.ru/test?theme=413
s = open('24_demo (1).txt').readline()
l = 0
r = 0
answ = 0
if s[0] == 'X':
    answ = 1
while r < len(s):
    if s[l] == 'X':
        if r + 1 < len(s) and s[r + 1] == 'X':
            r += 1
            answ = max(answ, r - l + 1)
        else:
            r += 1
            l = r
    else:
        l += 1
        r += 1
print(answ)