题解 | #字符个数统计#

import java.util.Scanner;

import java.io.*;
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) throws IOException{
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        String str;
        HashSet<Character> hs = new HashSet<>();
        while ((str = bf.readLine()) != null) {
            for (int i = 0; i < str.length(); i++) {
                char c = str.charAt(i);
                hs.add(c);
            }
            System.out.println(hs.size());
        }
    }
}