题解 | #字符个数统计#

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        HashSet<Object> hashSet = new HashSet<>();
        String str = scanner.next();
        char[] chars = str.toCharArray();
        for (char aChar : chars) {
            hashSet.add(aChar);
        }
        System.out.println(hashSet.size());
    }
}