import java.io.*;
import java.util.*;

public class Main{
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextLine()){
            String s = sc.nextLine();
            char[] cc = s.toCharArray();
            int count = 0;
            HashSet<Character> set = new HashSet<>();
            for(int i = 0; i < cc.length; ++i){
                if(cc[i] >= 0 && cc[i] <= 127){
                    if(!set.contains(cc[i])){
                        set.add(cc[i]);
                        count++;
                    }
                }
            }
            System.out.println(count);
        }
    }
}