#include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
using namespace std;

int main() {
	string s; cin >> s;
	int cnt = 0, ans = 0;
	rep(i, s.size()) {
		if (s[i] == 'B')cnt++;
		else ans += cnt;
	}
	cout << ans << endl;
}