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>

int main(void){
	int i,k,sign=0,sta=0;
	
	char s[200000];
	
	scanf(" %s",s);
	
	for(k=0;;k++){
		sign=0;
		for(i=sta;;i++){
			if(s[i]=='A'&&s[i+1]=='B'&&s[i+2]=='C'){
				s[i]='B'; s[i+1]='C'; s[i+2]='A';
				sign=1;
				sta=i-1;
				break;
			}
			if(s[i+2]=='\0'){
				break;
			}
		}
		if(sign==0){
			break;
		}
	}
	
	printf("%d\n",k);
	
	return 0;
}