#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <map>

#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define REP(i,a,n) for(int i = (a);i < (n);i++)
#define PI 3.14159265359
#define MOD 1000000007

using namespace std;

int main(){
    string s;
    cin >> s;
    int b = 0,ans = 0;
    REP(i, 0, s.length()){
        if(s[i] == 'B')b++;
        else ans += b;
    }
    cout << ans << endl;
    return 0;
}