using System;

namespace y
{
    class Program
    {
        static void Main(string[] args)
        {
            char[] c = Console.ReadLine().ToCharArray();
            int cnt = 0;

            for (int i = 0; i < c.Length - 1; i++)
            {
                for (int j = c.Length - 1; j > i; j--)
                {
                    if (c[j] < c[j -1])
                    {
                        char w = c[j];
                        c[j] = c[j -1];
                        c[j - 1] = w;
                        cnt++;
                    }
                }
            }

            Console.WriteLine(cnt);
        }
    }
}