agc034b.py

s = list(input())

i = 0
result = 0
while i < len(s) - 2:
  if s[i] != 'A':
    i += 1
    continue
  if s[i + 1] == 'B' and s[i + 2] == 'C':
    result += 1
    s[i] = 'B'
    s[i + 1] = 'C'
    s[i + 2] = 'A'
    if i != 0:
      i -= 1
  else:
    i += 1
print(result)