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 s = io.read()
local anum = 0
local num = 0
for i=1,string.len(s)-1 do
	local a = string.sub(s, i, i)
	local b = string.sub(s, i, i+1)
	if a == "A" then
		anum = anum + 1
	elseif  b == "BC" then
		num = anum + num
	else
		if i > 1 and string.sub(s, i-1, i) ~= "BC" then
			anum = 0
		end
	end
end
print(num)