#include <iostream>
using namespace std;
int n,sum,ans;
string s;
int main() {
	cin>>s;
	for(int i=s.size()-1;i>=0;i--){
		if(s[i]=='c'){
			sum++;
		}else if(s[i]=='a'){
			ans+=sum;
		}
	}
	cout<<ans;
	return 0;
}