#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;
}
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