using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;

namespace _0446
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = Console.ReadLine();
            var cnt = 0;
            var ans = 0;

            for (var i = 0; i < s.Length; i++)
            {
                if (s[i] == 'B')
                {
                    cnt++;
                }
                else
                {
                    ans += cnt;
                }
            }

            Console.WriteLine(ans);
        }
    }
}