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 C (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

int main(){

	int i, j, k, len, count = 0;
	char S[200000];

	scanf("%s", S);

	len = strlen(S);


	for (i = 1; i < len - 1; i++){
		if (S[i] == 'B' && S[i + 1] == 'C'){
			j = i;
			while (j - 1 >= 0 && S[j - 1] == 'A'){
				count++;
				j--;
			}
			S[j] = 'B';
			S[j + 1] = 'C';

			for (k = j + 2; k <= i + 1; k++){
				S[k] = 'A';
			}

			i++;
		}

//		printf("%s %d\n", S, i);
	}
	printf("%d\n", count);

  return 0;
}