import java.util.*;
//JAVA
//利用hashset去重,最后读取set的长度。
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
           Set outputSet = new HashSet();
           String inputStr = sc.nextLine();
           for(int i = 0; i<inputStr.length();i++){
                outputSet.add(inputStr.charAt(i));
            }
            System.out.println(outputSet.size());
        }
    }
}