using System;

namespace _559
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine(); int ret = 0; int now = 0;
            for (int i = 0; i < s.Length; i++)
            {
                if (s[i] == 'B') now++;
                else ret += now;
            }
            Console.WriteLine(ret);
        }
    }
}