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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.util.*
fun main(args: Array<String>){
	val cin = Scanner(System.`in`)
    val s = cin.next()

    var on = false
    var on_a_count = 0
    var bc = false
    var ans: Long = 0
    for (i in 0..s.length-1) {
        if (bc) {
            if (s[i] == 'C') {
                ans += on_a_count
            } else {
                on = false
            }
            bc = false
            continue
        }
        if (!on) {
            if (s[i] == 'A') {
                on = true
                on_a_count = 1
            }
        } else {
            if (s[i] == 'A') {
                on_a_count += 1
            } else if (s[i] == 'B') {
                bc = true
            } else {
                on = false
            }
        }
    }
    println(ans)
}