24 максимальная <= 3 X

s = open('').readline()
l = 0
r = 0
if s[0] == 'X':
    cnt_x = 1
else:
    cnt_x = 0
answ = 1
while r < len(s):
    if r + 1 < len(s) and (cnt_x < 3 or (cnt_x == 3 and s[r + 1] != 'X')):
        r += 1
        if s[r + 1] == 'X':
            cnt_x += 1
        answ = max(answ, r - l + 1)
    else:
        while s[l] != 'X':
            l += 1
        l += 1
        cnt_x -= 1
print(answ)