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 Scala (2.11.7) (judge verdict: Accepted)

import java.io._
import java.util.StringTokenizer
import scala.util.control.Breaks.{breakable,break}
import java.util.Scanner

object Main extends App {
  val in = new InputReader(System.in)
  val pw = new PrintWriter(System.out)

  //val sc = new Scanner(System.in)

  val s = in.next()
  //val s = sc.nextLine()

  var ans = 0L
  var cnt = 0L
  var i = 0
  while (i < s.length - 1) {
    val now = s(i)
    if (now == 'A') {
      cnt += 1
      i += 1
    }
    else if (now == 'C') {
      cnt = 0
      i += 1
    }
    else if (now == 'B') {
      if (s(i+1) == 'C') {
        ans += cnt
        i += 2
      }
      else {
        cnt = 0
        i += 1
      }
    }
  }
  println(ans)
}


class InputReader(stream: InputStream) {
  private val reader = new BufferedReader(new InputStreamReader(stream))
  private var tokenizer: StringTokenizer = new StringTokenizer(reader.readLine())
  def next(): String = {
    while (!tokenizer.hasMoreTokens()) {
      tokenizer = new StringTokenizer(reader.readLine())
    }
    tokenizer.nextToken()
  }
}