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>) {
    agc034b()
}

// 愚直じゃないよね？？
fun agc034b() {
    val s = readLine()!!.toCharArray()

    var before: CharArray
    val abc = "ABC"
    var answer = 0L
    while (true) {
        before = s.copyOf()
        for (i in 0..s.lastIndex - 2) {
            val slice = s.slice(i..i + 2).toCharArray()
            if (slice.toString() == abc) {
                s[i] = 'B'
                s[i + 1] = 'C'
                s[i + 2] = 'A'
                answer++
            }
        }
        if (s.toString() == before.toString()) break
    }

    println(answer)
}