/*~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
*$* WRITER:kakitamasziru/OxOmisosiru *$*
~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=*/
#ifdef LOCAL_JUDGE
#define _GLIBCXX_DEBUG //FOR THE DEBUG! COMMENT OUT THIS WHEN SUBMITTING!
#endif
/* I REALLY HOPE MY WISH REACH YOU , ATCODER'S ONLINE JUDGE */
#define WOULD
#define YOU
#define PLEASE
#define ACCEPT
#define MY
#define SUBMISSION
/* I REALLY HOPE MY WISH REACH YOU , ATCODER'S ONLINE JUDGE */
#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <iomanip>
#include <limits>//setprecision
//#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <math.h>//pow,,,
#include <cmath>//abs,,,
#include <bitset> // bitset
//It is so troublesome that I include bits/stdc++.h !
using namespace std;

template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
const long long INF = 100100100100;
const long long MOD = 998244353;
typedef pair<int, int> P;
//NのM乗を求める(繰り返し二乗法)
long long mod_pow(long long N, long long M) {
	if (M == 0) return 1;
	long long res = mod_pow((N * N) % MOD, M / 2);
	//最下位ビット(*N)が1の時は単独でNをかける
	if (M & 1) res = (res * N) % MOD;

	return res %= MOD;
}
long long nCr(long long n, long long r) {
	long long A = 1, B = 1;
	//Aが分子Bが1/r!
	for (long long i = n - r + 1; i <= n; i++) {
		A = A * i % MOD;
	}
	for (long long i = 1; i <= r; i++) {
		B = B * i % MOD;
	}
	B = mod_pow(B, MOD - 2);
	B %= MOD;
	//Bは割るのではなく掛ける
	return (A * B) % MOD;
}

long long gcd(long long a, long long b) {
	if (b == 0) return a;
	else return gcd(b, a % b);
}

long long lcm(long long a, long long b) {
	return a * b / gcd(a, b);
}

//long long A,B;
bool ok(long long key, long long index) {
	if (index > key) return true;
	else if (index <= key) return false;
}
long long binary_search(long long key, long long size) {
	//left,right,midはいずれもindex
	long long left = -1, right = size;
	while (right - left > 1) {
		long long mid = left + (right - left) / 2;
		long long hantei = ok(key, mid);
		if (hantei) right = mid;
		else left = mid;
	}
	if (left == -1)return 0;
	return left;
}

int main() {
	string s; cin >> s;
	stack<char> A;
	string S;
	long long int ans = 0;
	if (s.size() == 1) {
		cout << 0 << endl;
		return 0;
	}
	//BCをDに置換してstackで扱いやすくする BCは崩れないので可能
	for (int i = 0; i < s.size() - 1; i++) {
	    if (s.at(i) == 'B' && s.at(i + 1) == 'C') {
	        S.push_back('D');
	        i++;
	        if (i == s.size() - 2) S.push_back(s.at(i + 1));
	    }
	    else {
	        S.push_back(s.at(i));
	    }
	}

	int renzokuA = 0;
	//stackするかと思ったけどswapが定数時間で神すぎる件について
	//と思ったけどよく考えたらA,Dをswapさせたら自動的にAが前にくる
	//なのでB,Cが登場するまでのAの個数を考えてれば、勝手に繋がってくれる
	for (int i = 0; i < S.size(); i++) {
		if (S.at(i) == 'A') renzokuA++;
		else if (S.at(i) != 'D') renzokuA = 0;
		if (S.at(i) == 'D') {
			ans += renzokuA;
		}
	}
	cout << ans << endl;
}


Measured memory_bytes: 776