#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T, typename A>
std::istream& operator>>(std::istream& is, std::vector<T, A>& v)
{
    for (auto& e : v) { is >> e; }
    return is;
}
template <typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template <typename T>
std::vector<T> readVec(const std::size_t l)
{
    std::vector<T> v(l);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T>
bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template <typename T>
bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
    return __builtin_ffsll(v);
#else
    return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//!==============================================================================================!//
//!  dP   dP   dP                            dP            dP      8888ba.88ba             dP    !//
//!  88   88   88                            88            88      88  '8b  '8b            88    !//
//!  88  .8P  .8P .d8888b. dP   .dP .d8888b. 88 .d8888b. d8888P    88   88   88 .d8888b. d8888P  !//
//!  88  d8'  d8' 88'  '88 88   d8' 88ooood8 88 88ooood8   88      88   88   88 88'  '88   88    !//
//!  88.d8P8.d8P  88.  .88 88 .88'  88.  ... 88 88.  ...   88      88   88   88 88.  .88   88    !//
//!  8888' Y88'   '88888P8 8888P'   '88888P' dP '88888P'   dP      dP   dP   dP '88888P8   dP    !//
//!==============================================================================================!//
template <std::size_t L>
class WaveletMatrix
{
public:
    using T = unsigned long long;
    template <typename InIt>
    WaveletMatrix(const InIt first, const InIt last) : sz(std::distance(first, last))
    {
        std::vector<bool> b(sz);
        std::vector<T> v(first, last);
        for (std::size_t i = 0, j = L - 1; i < L; i++, j--) {
            std::vector<T> z, o;
            for (std::size_t i = 0; i < sz; i++) { b[i] = (v[i] >> j) & 1, (b[i] ? o : z).push_back(v[i]); }
            table.push_back(FID{b}), v = z, zero.push_back(z.size());
            for (const T e : o) { v.push_back(e); }
        }
    }
    std::size_t noLessThan(std::size_t l, std::size_t r, const T v) const
    {
        assert(l < r);
        std::size_t ans = 0;
        for (std::size_t i = 0, j = L - 1; i < L; i++, j--) {
            const bool b = (v >> j) & 1;
            const std::size_t rl = table[i].rank(l), rr = table[i].rank(r);
            l = (b ? rl + zero[i] : l - rl), r = (b ? rr + zero[i] : r - rr), ans += (b ? 0 : rr - rl);
        }
        return r - l + ans;
    }
    std::size_t lessThan(const std::size_t l, const std::size_t r, const T v) const { return assert(l < r), r - l - noLessThan(l, r, v); }
    std::size_t rangeFreq(const std::size_t l, const std::size_t r, const T vinf, const T vsup) const { return assert(l < r), assert(vinf < vsup), noLessThan(l, r, vinf) - noLessThan(l, r, vsup); }
    std::size_t rank(const std::size_t l, const std::size_t r, const T v) const { return assert(l < r), rangeFreq(l, r, v, v + 1); }
    T quantile(std::size_t l, std::size_t r, std::size_t k) const
    {
        assert(l < r);
        std::size_t ans = 0;
        for (std::size_t i = 0, j = L - 1; i < L; i++, j--) {
            const std::size_t rl = table[i].rank(l), rr = table[i].rank(r);
            const bool b = rr - rl > k;
            l = (b ? rl + zero[i] : l - rl), r = (b ? rr + zero[i] : r - rr), k += (b ? 0 : k -= rr - rl), ans |= ((std::size_t)b << j);
        }
        return ans;
    }

private:
    class FID
    {
    private:
        using B = unsigned long long;
        static constexpr std::size_t BS = sizeof(B) * 8;
        const std::size_t sz;
        std::vector<B> data;
        std::vector<std::size_t> large;

    public:
        FID(const std::vector<bool>& b) : sz(b.size()), data((sz + BS) / BS, 0), large((sz + BS) / BS, 0)
        {
            std::size_t one = 0;
            for (std::size_t i = 0; i < sz; i++) {
                data[i / BS] |= ((B)b[i] << (i % BS)), one += b[i];
                if (i % BS == BS - 1) { large[(i + 1) / BS] = one; }
            }
        }
        bool operator[](const std::size_t n) const { return (data[n / BS] >> (n % BS)) & 1; }
        std::size_t rank(const std::size_t n) const { return large[n / BS] + (n % BS == 0 ? 0 : popCount(data[n / BS] & ((1ULL << (n % BS)) - 1))); }
    };
    const std::size_t sz;
    std::vector<std::size_t> zero;
    std::vector<FID> table;
};
//!============================================!//
//!    8888ba.88ba             oo              !//
//!    88  '8b  '8b                            !//
//!    88   88   88  .d8888b.  dP  88d888b.    !//
//!    88   88   88  88'  '88  88  88'  '88    !//
//!    88   88   88  88.  .88  88  88    88    !//
//!    dP   dP   dP  '88888P8  dP  dP    dP    !//
//!============================================!//
int main()
{
    const auto S = read<std::string>();
    const int N = S.size();
    std::vector<int> v;
    for (int p = 0, base = 0; p < N; p++) {
        if (S[p] == 'A') {
            v.push_back(base + 1);
        } else if (p + 1 < N and S[p] == 'B' and S[p + 1] == 'C') {
            v.push_back(base), p++;
        } else {
            base += 2;
        }
    }
    WaveletMatrix<20> wm(v.begin(), v.end());
    ll ans = 0;
    for (int i = 0; i < v.size(); i++) { ans += wm.lessThan(i, v.size(), v[i]); }
    std::cout << ans << std::endl;
    return 0;
}


Measured memory_bytes: 7476