题解 | #字符个数统计#

import java.util.*;

public class Main{

public static void main(String[] args){
    
    Scanner sc = new Scanner(System.in);
    String str = sc.nextLine();
    char[] cha = str.toCharArray();
    HashSet<Character> hashset = new HashSet();
    for(int i=0;i<cha.length;i++){
        hashset.add(cha[i]);
    }
    System.out.println(hashset.size());
}

}