#include <iostream>
using namespace std;
 
int main(){
    string S;
    cin >> S;
    int ans = 0;
    int digit_B = 0;
    for(int i = 0; i < S.size(); i++){
        if(S[i] == 'B'){
            ans += S.size() - i;
            digit_B++;
        }
    }
    cout << ans - digit_B * (digit_B + 1) / 2 << endl;
}