# import re
#
# with open('24_7.txt', 'r') as file:
#     data = file.readline()
#
# data = re.sub('CD', '--', data)
#
# not_CD = r'(-?[^-]*)'
#
# CD_and_any = r'(?:--[^-]*){160}-?'
# la_CD_group = rf'(?=({CD_and_any}))'
#
# pattern = rf'{not_CD}{la_CD_group}'
#
# matches = re.findall(pattern, data)
#
# res = max([len(match[0] + match[1])
#            for match in matches])


# f = open('24_7.txt').read().strip()
# a = []
# for i in range(len(f) - 1):
#     if f[i]+f[i+1] == 'CD':
#         a.append(i)
# print(max([p1-p for p,p1 in zip(a, a[161:])]))







f = open('24_7.txt').read().strip()
cd = 0
two = 0
max_len = 0

for i in range(len(f)-1):
    if f[i] + f[i+1]== 'CD':
        cd += 1

    while cd > 160:
        if f[two]=='C' and f[two+1] == 'D':
            cd -= 1
        two += 1

    if cd == 160:
        max_len = max(max_len, i - two+2)

print(max_len)