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 Julia (0.5.0) (judge verdict: Time Limit Exceeded)

function read_line()
    map(x->parse(Int64, x), split(readline()))
end
function solve()
    ret = 0
    S = collect(strip(readline()))
    i = 1
    while i < length(S) - 1
        if S[i:i+2] == ['A', 'B', 'C']
            S[i] = 'B'
            S[i+1] = 'C'
            S[i+2] = 'A'
            ret += 1
            if i > 1
                i -= 1
            end
        else
            i += 1
        end
    end
    println(ret)
end
solve()