#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
using pll = pair<ll,ll>;
constexpr int INF = 1e9;
constexpr ll LINF = 1e18;
constexpr int MOD = 1000000007;

int main(){
    string s;
    cin >> s;
    int ans = 0;
    int b = 0;
    rep(i,s.size()){
        if(s[i] == 'B') ++b;
        else ans += b;
    }
    cout << ans << endl;
    return 0;
}