#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

int find_B(string S) {
  for (int i = 0; i < S.size(); i++) {
    if (S[i] == 'B')
      return i;
  }
  return -1;
}

int main() {
  string S;
  cin >> S;
  vector<int> B_locations;
  int B_counts = 0;
  if (S.size() == 1) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 0; i < S.size(); ++i) {
    if (S[i] == 'B') {
      B_locations.push_back(i);
      ++B_counts;
    }
  }
  sort(B_locations.begin(), B_locations.end(), greater<int>());
  int answer = 0;
  for (int i = 0; i < B_locations.size(); ++i) {
    answer += S.size() - i - B_locations[i] - 1;
  }
  cout << answer << endl;
  return 0;
}