#include <bits/stdc++.h>
using namespace std;
typedef long long   signed int LL;
typedef long long unsigned int LU;
#define incID(i, l, r) for(LL i = (l)    ; i <  (r); ++i)
#define incII(i, l, r) for(LL i = (l)    ; i <= (r); ++i)
#define decID(i, l, r) for(LL i = (r) - 1; i >= (l); --i)
#define decII(i, l, r) for(LL i = (r)    ; i >= (l); --i)
#define inc(i, n)  incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec(i, n)  decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))
#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
template<typename T> bool setmin  (T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmax  (T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
LL mo(LL a, LL b) { assert(b > 0); a %= b; if(a < 0) { a += b; } return a; }
LL fl(LL a, LL b) { assert(b > 0); return (a > 0 ? a / b : (a - b + 1) / b); }
LL ce(LL a, LL b) { assert(b > 0); return (a < 0 ? a / b : (a + b - 1) / b); }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
#define bit(b, i) (((b) >> (i)) & 1)
#define BC __builtin_popcountll
#define SC static_cast
#define SI(v) SC<int>(v.size())
#define SL(v) SC<LL >(v.size())
#define RF(e, v) for(auto & e: v)
#define ef else if
#define UR assert(false)

// ---- ----

template<typename T> class SegmentTree {
private:
	T * a = NULL;
	int N = -1, S;
	function<T(T, T)> F;
	T I;
	bool is_available = false;
public:
	SegmentTree() { }
	SegmentTree(int n, function<T(T, T)> func, T id) { init(n, func, id); }
	void init(int size, function<T(T, T)> func, T id) {
		assert(size > 0);
		N = size;
		F = func;
		I = id;
		S = 1;
		while(S < size) { S *= 2; }
		delete[] a;
		a = new T[S * 2];
		inc(i, S * 2) { a[i] = I; }
		is_available = true;
	}
	const T & operator[](int p) {
		assert(inID(p, 0, N));
		p += S;
		return a[p];
	}
	T & ref(int p) {
		is_available = false;
		assert(inID(p, 0, N));
		p += S;
		return a[p];
	}
	void calc() {
		decID(i, 1, S) { a[i] = F(a[i * 2], a[i * 2 + 1]); }
		is_available = true;
	}
	void apply(int p, function<void(T &)> op) {
		assert(inID(p, 0, N));
		p += S;
		op(a[p]);
		while(p != 1) {
			p /= 2;
			a[p] = F(a[p * 2], a[p * 2 + 1]);
		}
	}
	T fold_ID(int l, int r, bool loop = false) {
		assert(is_available);
		assert(inII(l, 0, N));
		assert(inII(r, 0, N));
		if(loop && l >= r) { return F(fold_ID(l, N), fold_ID(0, r)); }
		assert(l <= r);
		l += S;
		r += S;
		T v = I, w = I;
		while(l < r) {
			if(l + 1 == r) { v = F(v, a[l]); break; }
			if(l % 2 == 1) { v = F(v, a[l]); }
			if(r % 2 == 1) { w = F(a[r - 1], w); }
			l = (l + 1) / 2;
			r = r / 2;
		}
		return F(v, w);
	}
	T fold_II(int l, int r, bool loop = false) { return fold_ID(l    , r + 1, loop); }
	T fold_CD(int l, int r, bool loop = false) { return fold_ID(l + 1, r    , loop); }
	T fold_CI(int l, int r, bool loop = false) { return fold_ID(l + 1, r + 1, loop); }
};

#define OP(op) [&](auto A, auto B) { return op; }
#define AP(op) [&](auto & A) { op; }

// ---- ----

string s;

int main() {
	cin >> s;
	s += "x";
	
	LL ans = 0;
	vector<int> v;
	inc(i, SI(s)) {
		if(s[i] == '@') { }
		ef(s[i] == 'A') { v.PB(1); }
		ef(s.substr(i, 2) == "BC") { v.PB(0); s[i + 1] = '@'; }
		else {
			if(SI(v) == 0) { continue; }
			
			SegmentTree<int> st(SI(v), OP(A + B), 0);
			inc(j, SI(v)) {
				if(v[j] == 0) { ans += st.fold_ID(0, j); }
				else { st.apply(j, AP(A++)); }
			}
			v.clear();
		}
	}
	
	cout << ans << endl;
	
	return 0;
}


Measured memory_bytes: 3448