/*vvv>
		zzzzzI
 .---.  zzuzuI                 .vgggg&,.
+++++=  dunkoI  .WbbWo       JMM9^```?TMB`  ..&gNNg,.   gggggggJ,   qgggggggg] (&&&&&&&&[   c+OA&J,   (&&&&&&+J,   .cJeAA&-.  (&&&&&&&&x   .&AA&=-.
+++++=  dunkoI  Xpbpbp      JM#`           (M#^   ?MMp  MM|   +TMN. JMF      ' |yk      ` dVY    7Vk,  Vy     XV  cVf     ?Y!  JM         V$      `
+++++=  OunkoI  Xppppp      dMN           .MM+     .MM  MM|     MM] JMMMMMM+   |@tqkoh)  ,y0      (V$  yyyyyyyV7  VV           JMWyZWr    TWVVVVW&,
++++++  dZZZZ0  Xppppp      ^HMN,    _.db  WMm,   .MMF  MM|   ..MM` JMF      . |yk       .WV&.   .XW'  yy   4yn.  jyn      +.  JM                #S
`++++`  ?ZZZX=  ?WWWW=        -THMMMMH9^    (TMMMMM9!   MMMMMMM""   JMMMMMMMME |UU.        ?TUUUUY=    UU.   (UU-  ^7TUUUV7!   JUUUUUUUU  7TUNKO*/

//Ricty Diminished
#include "bits/stdc++.h"
using namespace std;typedef long long lint;typedef vector<lint> liv;
//#define rep(i,n) for(int i=0;i<n;++i)
#define all(v) v.begin(),v.end()
#define linf 1152921504606846976
#define MAXN 100100
#define md 1000000007//998244353

#define pb push_back
#define _vcppunko4(tuple) _getname4 tuple
#define _getname4(_1,_2,_3,_4,name,...) name
#define _getname3(_1,_2,_3,name,...) name
#define _trep2(tuple) _rep2 tuple
#define _trep3(tuple) _rep3 tuple
#define _trep4(tuple) _rep4 tuple
#define _rep1(n) for(lint i=0;i<n;++i)
#define _rep2(i,n) for(lint i=0;i<n;++i)
#define _rep3(i,a,b) for(lint i=a;i<b;++i)
#define _rep4(i,a,b,c) for(lint i=a;i<b;i+=c)
#define _trrep2(tuple) _rrep2 tuple
#define _trrep3(tuple) _rrep3 tuple
#define _trrep4(tuple) _rrep4 tuple
#define _rrep1(n) for(lint i=n-1;i>=0;--i)
#define _rrep2(i,n) for(lint i=n-1;i>=0;--i)
#define _rrep3(i,a,b) for(lint i=b-1;i>=a;--i)
#define _rrep4(i,a,b,c) for(lint i=a+(b-a-1)/c*c;i>=a;i-=c)
template<class T>
istream& operator>>(istream& is,vector<T>& vec);
template<class T,size_t size>
istream& operator>>(istream& is,array<T,size>& vec);
template<class T,class L>
istream& operator>>(istream& is,pair<T,L>& p);
template<class T>
ostream& operator<<(ostream& os,vector<T>& vec);
template<class T,class L>
ostream& operator<<(ostream& os,pair<T,L>& p);
template<class T>
istream& operator>>(istream& is,vector<T>& vec){ for(T& x: vec) is>>x;return is; }
template<class T,class L>
istream& operator>>(istream& is,pair<T,L>& p){ is>>p.first;is>>p.second;return is; }
//template<class T>
//ostream& operator<<(ostream& os,vector<T>& vec){ os<<vec[0];rep(i,1,vec.size())os<<' '<<vec[i];return os; }
//template<class T>
//ostream& operator<<(ostream& os,deque<T>& deq){ os<<deq[0];rep(i,1,deq.size())os<<' '<<deq[i];return os; }
template<class T,class L>
ostream& operator<<(ostream& os,pair<T,L>& p){ os<<p.first<<" "<<p.second;return os; }

inline void in(){}
template <class Head,class... Tail>
inline void in(Head&& head,Tail&&... tail){ cin>>head;in(move(tail)...); }
template <class T>
inline bool out(T t){ cout<<t<<'\n';return 0; }
inline bool out(){ cout<<'\n';return 0; }
template <class Head,class... Tail>
inline bool out(Head head,Tail... tail){ cout<<head<<' ';out(move(tail)...);return 0; }

template<typename T>
vector<T> make_v(size_t a){ return vector<T>(a); }

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
	return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V>
typename enable_if<is_class<T>::value==0>::type
fill_v(T &t,const V &v){ t=v; }

template<typename T,typename V>
typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t,const V &v){
	for(auto &e:t) fill_v(e,v);
}//http://beet-aizu.hatenablog.com/entry/2018/04/08/145516

#define rep(...) _vcppunko4((__VA_ARGS__,_trep4,_trep3,_trep2,_rep1))((__VA_ARGS__))
#define rrep(...) _vcppunko4((__VA_ARGS__,_trrep4,_trrep3,_trrep2,_rrep1))((__VA_ARGS__))
#define each(v) for(auto &i:v)
#define lin(...) lint __VA_ARGS__;in(__VA_ARGS__)
#define stin(...) string __VA_ARGS__;in(__VA_ARGS__)
#define vin(type,name,size) vector<type> name(size);in(name)
#define fi i.first
#define se i.second
#define YES(c) cout<<((c)?"YES\n":"NO\n"),0
#define Yes(c) cout<<((c)?"Yes\n":"No\n"),0
#define o(p) cout<<p<<endl,0
#define sp(p) cout<<p<<" "
#define deb(p) cerr<<p<<endl,0
#define dd(n) cout<<fixed<<setprecision(n)

#define inf linf

//死ね
//int main(){
//	lint n,a,b,c,d;in(n,a,b,c,d);--a;--b;--c;--d;
//	stin(s);
//	int ans=1,nukasu=0,aku=0;
//	if((a<b)^(c<d))nukasu=(a>b?1:2);
//	rep(i,a,min(c-1,n-1)){
//		if(s[i]=='#'&&s[i+1]=='#')ans=0;
//	}
//	rep(i,max({a,b,1ll})-1,min({c,d,n-1})-1){
//		if(s[i]=='.'&&s[i+1]=='.'&&s[i+2]=='.')aku=1;
//	}
//	rep(i,b,min(d-1,n-1)){
//		if(s[i]=='#'&&s[i+1]=='#')ans=0;
//	}
//	if(nukasu&&!aku)ans=0;
//	Yes(ans);
//}

int main(){
	stin(s);
	lint n=s.size(),ans=0,a=0,f=0;
	rep(n-2){
		if(!a&&s[i]=='A')f=i;
		if(s[i]=='A')++a;
		else a=0,f=i;
		if(s[i]=='A'&&s[i+1]=='B'&&s[i+2]=='C')
			s[i+1]='A',s[i+2]='A',s[f]='B',s[f+1]='C',s[f+2]='A',ans+=a,a-=2,f=f+2;
	}
	o(ans);
}

//sub_EOF

//map<lint,lint> zip;
//lint unzip[MAXN];
//
//void compress(vector<lint> &a,map<lint,lint> &z,lint u[]){
//	vector<lint> v=a;
//	sort(all(v));
//	v.erase(unique(all(v)),v.end());
//	rep(i,v.size()){
//		z[v[i]]=i;
//		u[i]=v[i];
//	}return;
//}
//
//int main(){
//	lint n,qn;in(n,qn);
//	vector<lint> a;
//	struct query{ lint t,x,y; };
//	vector<query>q(n);
//	rep(qn){
//		cin>>q[i].t>>q[i].x>>q[i].y;
//		a.pb(q[i].x);
//		a.pb(q[i].y);
//	}compress(a,zip,unzip);
//	lint m=a.size();
//}

//sub-EOF


Measured memory_bytes: 640