---

s = open('24.txt').readline()
m=0
count_bc=0
for l in range(len(s)):
    if s[l-1]=='B' and s[l]=='C':
        count_bc-=1

    for r in range(l+m, len(s)):
        c=s[l:r+1]
        if c[-2] == 'BC': count_bc +=1
        if c.count('BC')>180: break
        m=max(m, len(c))
    if l%100000==0:
        print(l, m, len(c))
print(m)