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 Perl (v5.18.2) (judge verdict: Time Limit Exceeded)

use strict;
use warnings;

chomp(my $s = <>);

my $cnt = 0;

while ($s =~ m/ABC/) {
	$s =~ s/(.*)A((?:BC)+)/$1$2A/;
	my $add = (length $2) / 2;
	$cnt += $add;
}

print $cnt, "\n";