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 JavaScript (node.js v5.12) (judge verdict: Runtime Error)

function Main(stdin) {
  stdin = stdin.split('\n')
  const input = stdin[0].split('')
  let isChange = true
  const start = 0
  let count = 0
  while (isChange) {
    isChange = false
    for (let i = start; i < input.length; i++) {
      if (input[i] === 'A' && input[i + 1] === 'B' && input[i + 2]) {
        swap(input, i)
        count = count + 1
        isChange = true
        i = i + 1
      }
    }
  }
  console.log(count)
}

function swap(input, start) {
  input[start] = 'B'
  input[start + 1] = 'C'
  input[start + 2] = 'A'
}

Main(require('fs').readFileSync('/dev/stdin', 'utf8'))