#include <bits/stdc++.h>
using namespace std;
int solve(string s) {
	int ret = 0;
	for(int i = 0; i < s.size(); i++) {
		if(s[i] == 'B') ret += i;
	}
	return ret;
}
string x;
int main() {
	cin >> x;
	int ret = solve(x);
	sort(x.begin(), x.end());
	cout << solve(x) - ret << endl;
	return 0;
}