#include "bits/stdc++.h"
using namespace std;
#define Would
#define you
const int INF = 999999999;
const int MOD = 1e9 + 7;
const double pi = 3.141592653589793238;

int a, b;
int main() {
	string h;
	cin >> h;
	for (int i = 0; i < h.length(); ++i) {
		if (h[i] == 'B') { ++b; }
		else { a += b; }
	}
	cout << a << endl;
}