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 s = sc.nextLine();
    Map<String,String> objects = new HashMap<>();
    for (int i = 0; i < s.length(); i++) {
        objects.put(Character.toString(s.charAt(i)),"1");
    }
    Set<String> longs = objects.keySet();
    System.out.println(longs.size());
}

}