PhonePe2019D

/*
Author: Mehul Chaturvedi
*/

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define vll vector<long long>
#define rep(i, n) for (int i = 0, _n = (n); i < _n; i++)

/*
* ..AAABCBC...BC.. Now, k continuous A, and l continuous BC after those A
* Will result in k*l operations. Also note that this will shift those k As
* to the right of all BCs, so keep that buffer count in case you encounter
* As again after the BCs
*/
void solve() {
    string s; cin >> s;
    ll n = s.size();

    ll ans = 0ll;
    ll i = 0ll;
    ll prevA = 0;
    while (i < n) {
        if (s[i] == 'A') {
            ll count = 0ll;
            while (i < n && s[i] == 'A') {
                count++;
                i++;
            }
            count += prevA;
            prevA = count;
            ll count2 = 0ll;
            while (i < n - 1 && s[i] == 'B' && s[i + 1] == 'C') {
                count2++;
                i++;
                i++;
            }

            ans += count * count2;
        } else {
            prevA = 0;
            i++;
        }
    }

    cout << ans << '\n';
    return;
}

int main(int argc , char ** argv) {
    ios_base::sync_with_stdio(false) ;
    cin.tie(NULL) ;

    ll t = 1;

    while (t--) {
        solve();
    }

    return 0 ;
}