#include <bits/stdc++.h>
using namespace std;

int main() {
  string s;
  cin >> s;

  int cnt = 0;
  int ans = 0;
  for (int i = 0; i < s.size(); ++i) {
    if (s[i] == 'B') cnt++;
    else ans += cnt;
  }

  cout << ans << endl;
}