N10

s = ''
with open('24.txt') as f:
    s = f.readline()

s = s.replace('AA', '*')
a = s.split('*')
#print(s)
#print(a)

kmax = 1
#1, posl - otdel
t = a[0]
if len(t) != 0:
    k = len(t) + 1
    if t[-1] == 'A':
        k -= 1
    kmax = max(k, kmax)

t = a[-1]
if len(t) != 0:
    k = len(t) + 1
    if t[0] == 'A':
        k -= 1
    kmax = max(k, kmax)

for i in range(1, len(a) - 1):
    t = a[i]
    if len(t) == 0:
        continue
    k = len(t) + 2
    if t[0] == 'A':
        k -= 1
    if t[-1] == 'A':
        k -= 1
    kmax = max(k, kmax)
print(kmax)