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

s.gsub!(/BC/, "D")

k = s.split(/[BC]++/)

count = 0
a = 0

k.each{ |str|
  str.length.times{|i|
    if str[i] == "A" then
      a += 1
    elsif str[i] == "D" then
      count += a
    end
  }
  a = 0
}

p count