#include "bits/stdc++.h"

#define rep(a,b) for(int a = 0;a < b;a++)
#define REP(i, x, n) for(int i = x; i < n; i++)
#define P(a) cout << a << endl
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
int dx[] = { 1, -1 , 0 , 0 };
int dy[] = { 0,  0,  1, -1 };
ll MOD = 1000000007;
unsigned long long str_to_int(std::string str) {
  unsigned long long ret;
  std::stringstream ss; ss << str;
  ss >> ret;
  return ret;
}

int main() {
    string s;
    cin >> s;
    int count = 0;
    int last = s.length()-1;
    for(int i = s.length()-1;i >= 0;i--){
        if(s[i] == 'B'){
            count += abs(last-i);
            last--;
        }
    }
    cout << count << endl;
}