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: Wrong Answer)

local str = io.read()
local index = 1
local tStr = {}
for i = 1, #str do
    tStr[i] = string.sub(str, i, i)
end
local sum = 0
local a = 0
for i = index, #str do
    if tStr[i] == "A" then
        a = a + 1
    elseif (tStr[i]  == "C" and (i > 1 and tStr[i - 1]  ~= "B")) or (tStr[i]  == "B" and (i > 1 and tStr[i - 1]  == "B")) then
        a = 0
    elseif  tStr[i]  == "B" and  (i + 1 <= #tStr and tStr[i + 1]  == "C") then
        sum = sum + a
        i = i + 1
    end
end
print(sum)