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);
}
}

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