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: Time Limit Exceeded)

fun main(args: Array<String>) {
    val s = readLine()!!.toCharArray()
    var count = 0
    do {
        val replaced = replace(s)
        count += replaced
    } while (replaced > 0)
    println(count)
}

fun replace(charArray: CharArray): Int {
    for (i in 0 .. charArray.size - 3) {
        if (charArray[i] == 'A'
            && charArray[i + 1] == 'B'
            && charArray[i + 2] == 'C'
        ) {
            charArray[i] = 'B'
            charArray[i + 1] = 'C'
            charArray[i + 2] = 'A'
            return 1
        }
    }
    return 0
}