чередование согл+гласн

f = open('24.txt').readline()
answ = 0
cur = 0
s = ['CDF', 'AO']
for i in range(len(f)):
    if f[i] in s[cur % 2]:
        cur += 1
        if cur > answ:
            answ = cur
    else:
        cur = 0
print(answ)