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: Time Limit Exceeded)

S = gets.chomp
ans = 0
if S.size >= 3
  0.upto(S.size()-2) do |i|
    if S[(i)..(i+2)] == 'ABC'
      tmp=0
      j=i
      while j>=0 do
        if S[j] == 'A'
          tmp+=1
          j-=1
        else
          break
        end
      end
      ans+=tmp
      s='BC'+'A'*tmp
      S[(j+1)..(j+s.size())]=s
    end
  end
end
puts ans