Задание №61544 ЕГЭ Информатике

f=open(r'24.txt')
s=f.read()
count=0
max_count=0
i=0
while i < len(s):
    if (s[i]=='C' or s[i]=='D' or s[i]=='F') and (s[i+1]=='A' or s[i+1]=='O'):
        count+=1
        i+=2
        if max_count < count:
            max_count=count
    else:
        count=0
        i+=1
print(max_count)