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

int main() {
  string s;
  cin >> s;
  int cnt = 0;
  int ans = 0;
  for (int i = 0; i < int(s.size()); ++i) {
    if (s[i] == 'B') continue;
    ans += i - cnt++;
  }
  cout << ans << endl;
  return 0;
}