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()
{
    char s[300000];
    scanf("%s",&s);
    int i,oldcounter=0,counter=0;

    do
    {
        oldcounter=counter;
        for(i=0;i<199998;i++)
        {
            if(s[i]=='A'&&s[i+1]=='B'&&s[i+2]=='C')
            {
                s[i]='B';
                s[i+1]='C';
                s[i+2]='A';
                counter++;
                //printf("qwertyui\n");
            }
        } 
        //printf("%s\n",s);
    } while (counter!=oldcounter);
    printf("%d\n",counter);
    return 0;
}