using System;
using System.Collections.Generic;

class Buchongfu
{
    static void Main()
    {
        Dictionary<int, char> Dic = new Dictionary<int, char>();

        string Zoo = Console.ReadLine();

        int Chang = Zoo.Length;
        int n = 0;

        for (int i = 0; i< Chang;  i++)
        {
            if(! Dic.ContainsValue(Zoo[i]) )
            {
                n++;
                Dic.Add(n, Zoo[i]);
            }
        }


            Console.WriteLine(n);
    }
}