// Original C++ solution (slower):
/**

    OJ :

    Program Code :

    Md. Mujahedul Azad (Turin)

    Hajee Mohammad Danesh Science & Technology University

**/



#include <map>

#include <set>

#include <queue>

#include <stack>

#include <cctype>

#include <cstdio>

#include <math.h>

#include <string>

#include <vector>

#include <cassert>

#include <climits>

#include <cstdlib>

#include <cstring>

#include <iomanip>

#include <sstream>

#include <utility>

#include <iostream>

#include <iterator>

#include <algorithm>

/// #include<bits/stdc++.h>

using namespace std;



#define ff              first

#define se              second

#define nl              << '\n'

#define gf              << ' ' <<

#define pb              push_back

#define pi              2*acos(0.0)

#define sq(a)           ((a) * (a))

#define Sort(a)         sort(all(a))

#define sz(x)           (int)x.size()

#define fillAra(a,n,v)  fill(a, a+n, v)

#define fillVec(a, v)   fill(all(a), v)

#define btz(a)          __builtin_ctz(a)

#define all(v)          v.begin(),v.end()

#define max3(a,b,c)     max(a, max(b, c))

#define min3(a,b,c)     min(a, min(b, c))

#define abs(x)          (((x)<0)?-(x):(x))

#define parity(a)       __builtin_parity(a)

#define maxall(v)       *max_element(all(v))

#define minall(v)       *min_element(all(v))

#define cinIg           cin.sync(); cin.get()

#define countOne(a)     __builtin_popcount(a)

#define mem(a,v)        memset(a, v, sizeof(a))

#define RSort(a)        Sort(a), reverse(all(a))

#define precision(x)    cout << setprecision(x) << fixed

#define un(a)           Sort(a), (a).erase(unique(all(a)),a.end())

#define FasterIO        ios_base::sync_with_stdio(false);cin.tie(NULL)

#define TestCases       int cases, tc; sfi(tc); for(cases=1; cases<=tc; cases++)

#define TestCasespp     int cases, tc; cin>>tc; for(cases=1; cases<=tc; cases++)

#define common(a,b)     Sort(a), Sort(b), a.erase(set_intersection(all(a), all(b), a.begin()), a.end())

#define uncommon(a,b)   Sort(a), Sort(b), a.erase(set_symmetric_difference(all(a), all(b), a.begin()), a.end())



/**------- ShortCuts----------*/

typedef long long             ll;

typedef unsigned long long    ull;

typedef double                db;

typedef long double           ldb;

typedef pair<int, int>        pii;

typedef pair<ll, ll>          pll;

typedef pair<int, pii>        iii;

typedef vector<int>           vi;

typedef vector<ll>            vl;

typedef vector<pii>           vii;

typedef vector<iii>           viii;

typedef vector<vi>            vvi;

typedef map<int, int>         mapii;

typedef map<int, bool>        mapib;

typedef map<int, string>      mapis;

typedef set<int>              seti;



/**------- Char Chk----------*/

inline bool isLow(char ch){if(ch>='a' && ch<='z') return true; return false;}

inline bool isUpp(char ch){if(ch>='A' && ch<='Z') return true; return false;}

inline bool isDig(char ch){if(ch>='0' && ch<='9') return true; return false;}



/**------- Double Chk----------*/

inline bool are_equal(db a, db b){return fabs(a-b)<numeric_limits<db>::epsilon();}

inline bool less_than(db a, db b){return (b-a) > ((fabs(a)<fabs(b)?fabs(b):fabs(a)) * numeric_limits<db>::epsilon());}

inline bool greater_than(db a, db b){return (a-b) > ((fabs(a)<fabs(b)?fabs(b):fabs(a)) * numeric_limits<db>::epsilon());}



/**------- Functions ---------*/



template<typename T> string toString(T x){stringstream ss; ss<<x; return ss.str();}

template<typename T> T stringToT(string s, T a){T p; istringstream ss(s); ss>>p; return p;}

template<typename T> T SOD(T n){__typeof(n) sum=0, i=1; for(; i*i<=n; i++) sum += (n%i)?0:((sq(i)==n)?i:i+n/i); return sum;}

template<typename T, typename S> ostream& operator << (ostream& os, const pair<T, S> &v){os << "(" << v.ff << ", " << v.se << ")";return os;}

template<typename T, typename S> ostream& operator << (ostream& os, const map<T, S> &v){for(auto it : v) os << it.ff << " : " << it.se nl; return os;}

template<typename T>ostream& operator << (ostream& os, const set<T> &v){ os << "["; for(auto it : v){os << it;if(it != *v.rbegin())os << ", ";}os << "]";return os;}

template<typename T>ostream& operator << (ostream& os, const vector<T> &v){os << "["; for(int i=0; i<v.size(); i++){ os << v[i]; if(i != sz(v)-1) os << ", ";} os << "]"; return os;}



/**--------Loops--------------*/

#define frab(i, a, b)      for(__typeof(b) i=(a); i<=(b); i++)

#define fr0(i, n)          frab(i, 0, n-1)

#define fr1(i, n)          frab(i, 1, n)

#define rfab(i, a, b)       for(__typeof(b) i=(b); i>=(a); i--)

#define rf0(i, n)           rfab(i, 0, n-1)

#define rf1(i, n)           rfab(i, 1, n)



/**------- Scanf----------*/

#define sf                 scanf

#define sfs(a)             scanf("%s", a)

#define sfc(a)             scanf("%c", &a)

#define sfi(a)             scanf("%d", &a)

#define sfd(a)             scanf("%lf", &a)

#define sfl(a)             scanf("%lld", &a)

#define sfu(a)             scanf("%llu", &a)

#define sfin(a, i, n)       fr0(i, n) sfi(a[i])

#define sfln(a, i, n)       fr0(i, n) sfl(a[i])

#define sfii(a, b)         scanf("%d %d", &a, &b)

#define sfdd(a, b)         scanf("%lf %lf", &a, &b)

#define sfll(a, b)         scanf("%lld %lld", &a, &b)

#define sfuu(a, b)         scanf("%llu %llu", &a, &b)

#define sfiii(a, b, c)     scanf("%d %d %d", &a, &b, &c)

#define sfddd(a, b, c)     scanf("%lf %lf %lf", &a, &b, &c)

#define sflll(a, b, c)     scanf("%lld %lld %lld", &a, &b, &c)

#define sfuuu(a, b, c)     scanf("%llu %llu %llu", &a, &b, &c)



/**------- Printf----------*/

#define pf                 printf

#define pnl                puts("")

#define pfgap              printf(" ")

#define pfig(a)            printf("%d ", a)

#define pfc(a)             printf("%c\n", a)

#define pfi(a)             printf("%d\n", a)

#define pfs(a)             printf("%s\n", a)

#define pflg(a)            printf("%lld ", a)

#define pfl(a)             printf("%lld\n", a)

#define pfu(a)             printf("%llu\n", a)

#define pfd(a)             printf("%.2lf\n", a)

#define pfii(a, b)         printf("%d %d\n", a, b)

#define pfll(a, b)         printf("%lld %lld\n", a, b)

#define pfuu(a, b)         printf("%llu %llu\n", a, b)

#define pfdd(a, b)         printf("%.2lf %.2lf\n", a, b)

#define pfiii(a, b, c)     printf("%d %d %d\n", a, b, c)

#define pflll(a, b, c)     printf("%lld %lld %lld\n", a, b, c)

#define pfuuu(a, b, c)     printf("%llu %llu %llu\n", a, b, c)

#define pfin(a, i, n)       fr0(i, n) {if(i) pfgap; pfig(a[i]);}

#define pfln(a, i, n)       fr0(i, n) {if(i) pfgap; pflg(a[i]);}

#define pfddd(a, b, c)     printf("%.2lf %.2lf %.2lf\n", a, b, c)



/**--------File------------*/

#define inOut              {input; output;}

#define Case               printf("Case %d: ", cases)

#define input              freopen("input.txt","r",stdin)

#define Casepp             cout << "Case " << cases << ": "

#define output             freopen("output.txt","w",stdout)



/**--------Constant------------*/

#define eps                1e-9

#define mx2                101

#define mx3                1001

#define mx4                10001

#define mx5                100001

#define mx6                1000001

#define INF                0x3f3f3f3f



/**-------Upper & Lower Bound-------*/

#define LB(a, v)            (lower_bound(all(a), v))

#define UB(a, v)            (upper_bound(all(a), v))



/**--------DeBug------------*/

#define watch(x)            cout<<(#x)<<" is "<<x<<"\n"

#define chk                 cout<<"Wtf"<<"\n"



const int mod = 1e9 + 7;

const int mx  = 2*mx5;



string s; int n;

bool ok(int p){

    return p>=0 && p+2<n && s[p]=='A' && s[p+1]=='B' && s[p+2]=='C';}



int main(){FasterIO;

    cin >> s; n = s.size();



    ll ans = 0, tmp = 0;

    for(int i=0; i<n; i++){

        if(ok(i)){

            ans += (++tmp); i++; i++; s[i] = 'A';

            if(ok(i)) tmp--, i--;

        }

        else if(s[i] == 'A') tmp++;

        else tmp = 0;

    }

    cout << ans nl;



    return 0;

}




// Optimized solution to the same problem (faster):
#include<cstdio>

#include<cstring>

using namespace std;



char s[200002];

int z[200001];

int main(){

	scanf("%s",s+1);

	int n=strlen(s+1);

	for(int i=1;i<=n;i++)

		if(s[i]=='A')z[++z[0]]=1;

		else if(i<n&&s[i]=='B'&&s[i+1]=='C')

			z[++z[0]]=2,i++;

		else z[++z[0]]=3;

	long long ans=0;

	for(int i=1;i<=z[0];i++){

		if(z[i]==3)continue;

		int j=i;

		while(j<=z[0]&&z[j]!=3)j++;

		int w=0;

		for(int k=i;k<=j;k++)

			if(z[k]==2)ans+=k-i-w,w++;

		i=j;

	}

	printf("%lld\n",ans);

}

// Fastest known solution for this problem: