#include <limits>
#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <map>
#include <queue>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using namespace std;

template<class T>
constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

int main() {
    string s;
    cin >> s;
    int k = 0, ans = 0;
    for (auto &&i : s) {
        if(i == 'B') k++;
        else ans += k;
    }
    cout << ans << "\n";
    return 0;
}