OIG XVI - ska

// https://szkopul.edu.pl/problemset/problem/bHstvzZhgVe2bVB3rjlhzMeg/site/?key=statement
// OIG XVI (1 etap)

#include <algorithm>
#include <iostream>

using namespace std;

int main() {
    string napis;
    cin >> napis;
    int iloscB = count(napis.begin(), napis.end(), 'B');
    int iloscC = count(napis.begin(), napis.end(), 'C');

    cout << iloscB / 2 + iloscC / 2;

    return 0;
}