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 (5.3.2) (judge verdict: Accepted)

local s = io.read()
local ret = 0
local cura = 0
local n = #s
local i = 1
while i <= n do
  local ss = s:sub(i, i)
  if ss == "A" then
    cura = cura + 1
    i = i + 1
  elseif ss == "B" then
    if i < n and s:sub(i + 1, i + 1) == "C" then
      ret = ret + cura
      i = i + 2
    else
      cura = 0
      i = i + 1
    end
  else
    cura = 0
    i = i + 1
  end
end
print(ret)