#define _CRT_SECURE_NO_WARNINGS #define _USE_MATH_DEFINES #include <iostream> #include <iomanip> #include <string> #include <cmath> #include <vector> #include <algorithm> #include <queue> #include <functional> #include <map> using namespace std; #define MOD 1000000007 #define INF 2147483647 #define ll long long int main() { string s; cin >> s; vector<int> B; for (int i = s.size() - 1; i >= 0; i--) { if (s[i] == 'B') { B.push_back(s.size() - i - 1); } } int cnt = 0; int res = 0; for (int i = 0; i < B.size(); i++) { res += B[i] - cnt; cnt++; } cout << res << endl; return (0); }