44

from itertools import product
f = open('24-157.txt')
frst = f.read(1)
cnt, cur_cnt = 1, 1
cmb = list(product('PQR', repeat=2))
while scnd := f.read(1):
    if tuple(frst+scnd) not in cmb:
        cur_cnt += 1
        if cur_cnt > cnt:
            cnt = cur_cnt
    else:
        cur_cnt = 1
    frst = scnd
print(cnt)