#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <fstream>
#include <set>
#include <utility>
#include <algorithm>
#include <queue>
#include <stack>
#include <deque>
#include <numeric>
#include <sstream>
#include <list>
#include <map>
#include <functional>
#include <iterator>


#define rep(i,p,n) for(int i=(int)p;i<(int)n;i++)
#define repp(i,p,n) for(int i=(int)p;i>=(int)n;i--)
#define Sort(x) sort(x.begin(),x.end());
#define PSort(x) sort(begin(x), end(x), pairCompare)
#define ll long long
#define INF 2000000000

using namespace std;

bool pairCompare(const std::pair<float, int>& firstElem, const std::pair<float, int>& secondElem) {
	return firstElem.first < secondElem.first;
}

int main() {
	int count = 0,ans=0;
	string s;
	cin >> s;
	count = s.length() - 1;
	for (int i = s.length() - 1; i >= 0; i--) {
		if (s[i] == 'B') {
			ans += count - i;
			count--;
		}
	}

	cout << ans << endl;

	return 0;
}