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 Lua (Lua 5.3.5) (judge verdict: Accepted)

local a = io.read("*l")
local b = {}
for i = 1, string.len(a) do
    table.insert(b,string.sub(a,i,i))
end

local total = 0

if #b >= 3 then
    local numA = 0
    local i = 0
    while i < #b do
        if b[i] == 'A' then
            numA = numA + 1
        elseif (b[i] == 'B' and b[i + 1] == 'C') then
            total = total + numA
            i = i + 1
        else
            numA = 0
        end

        i = i + 1
    end
end

print(total)