题解 | #字符个数统计#

import java.util.Scanner;
import java.util.HashMap;

// 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 in = new Scanner(System.in);
        String str = in.next();
        // 转换成数组 然后去重
        char[] chars = str.toCharArray();
        int len = chars.length;
        HashMap<Character, Character> map = new HashMap<>();
        for (int i = 0; i < len; i++) {
            if (!map.containsKey(chars[i])) {
                map.put(chars[i], chars[i]);
            }
        }
        System.out.println(map.size());
    }
}