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

#define int long long

#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;

template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

signed main(){
    string S;
    cin>>S;
    int cnt=0;
    int sum=0;
    rep(i,S.size()){
        if(S[i]=='B')continue;
        sum+=i-cnt;
        cnt++;
    }
    cout<<sum<<endl;
    return 0;
}