Problem:
Score : 600 points

Problem Statement

You are given a string s consisting of A, B and C.

Snuke wants to perform the following operation on s as many times as possible:

Choose a contiguous substring of s that reads ABC and replace it with BCA.

Find the maximum possible number of operations.

Constraints

1 \leq |s| \leq 200000

Each character of s is A, B and C.

Input

Input is given from Standard Input in the following format:

s

Output

Find the maximum possible number of operations.

Sample Input 1

ABCABC

Sample Output 1

3

You can perform the operations three times as follows: ABCABC → BCAABC → BCABCA → BCBCAA. This is the maximum result.

Sample Input 2

C

Sample Output 2

0

Sample Input 3

ABCACCBABCBCAABCB

Sample Output 3

6

Solution in Ruby (2.3.3) (judge verdict: Accepted)

S=gets.chomp

state = 0
acount = 0
ret = 0

S.each_char do |c|
#  p [c, state, acount,ret]
  case state
  when 0
    if c == 'A'
      acount += 1
      state = 1
    else
      acount = 0
    end
  when 1
    if c == 'A'
      acount += 1
    elsif c == 'B'
      state = 2
    else
      acount = 0
      state = 0
    end
  when 2
    if c == 'A'
      acount = 1
      state = 1
    elsif c == 'C'
      ret += acount
      state = 1
    else
      acount = 0
      state = 0
    end
  end
end

p ret