题解 | #字符个数统计#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String str = scan.nextLine();
        char[] chrs = str.toCharArray();
        HashSet<Character> hashSet = new HashSet<>();
        for (char chr : chrs) {
            hashSet.add(chr);
        }
        System.out.println(hashSet.size());
    }
}