题解 | #字符个数统计#

import java.util.*;

// 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.nextLine();
        HashSet<Character>set = new HashSet<>();
        int index = str.indexOf("\n");
        if (index > 0) {
            str = str.substring(0, index);
        }
        int size = str.length();
        int i = 0;
        while (i < size) {
            set.add(str.charAt(i));
            i++;
        }
        System.out.println(set.size());
    }
}