28(3)

with open('test.txt') as f:
    frst, snd, thrd, frth = str(), str(), str(), str()
    cnt = 0
    b = 0
    while a := f.read(1):
        frth = a
        if frst+snd+thrd+frth == 'XZZY':
            if cnt < b:
                cnt = b
            b = 0
        if frst+snd+thrd+frth == 'XZZY':
            b += 3
            if cnt < b:
                cnt = b
        else:
            b += 1
            if cnt < b:
                cnt = b
        frst, snd, thrd = snd, thrd, frth
print(cnt)