N11

f = open('24.txt')
s = f.readline()
f.close()

def d(x,y):
    global s
    s = s.replace(x,y)

d('A', 'X')
d('C', 'X')
d('D', 'X')
d('B', 'Y')
d('E', 'Y')
d('F', 'Y')

L = 1
R = len(s)
while L + 1 < R:
    M = (L + R) // 2
    if 'X' * M in s:
        L = M
    else:
        R = M
print(L)