题解 | #字符个数统计#

import java.util.HashSet;
import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNext()){
            String s = scanner.nextLine();
            String[] split = s.split("");
            HashSet<Object> objects = new HashSet<>();
            for (int i = 0; i <split.length; i++) {
                objects.add(split[i]);
            }
            System.out.println(objects.size());
        }
    }
}