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 PHP7 (7.0.15) (judge verdict: Time Limit Exceeded)

<?php
$str = trim(fgets(STDIN));
$len = strlen($str) - 2;
$count = 0;
for($i = 0; $i < $len; $i++){
  if($str[$i] == 'A' && $str[$i+1] == 'B' && $str[$i+2] == 'C'){
    $str[$i] = "B";
    $str[$i+1] = "C";
    $str[$i+2] = "A";
    $count++;
    $i-=2;
  }
}
echo $count;