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

public class yukicoder
{
    public static void Main()
    {
        char[] input = Console.ReadLine().ToCharArray();
        char temp;
        int ans = 0;
        
        for(int j = 0; j <= input.Length - 1; j++)
        {
            for(int i = 0; i < input.Length - 1; i++)
            {
                if(input[i] > input[i + 1])
                {
                    temp = input[i];
                    input[i] = input[i + 1];
                    input[i + 1] = temp;
                    ans ++;
                }
            }
        }
        
        Console.WriteLine(ans);

    }
}