题解 | #字符个数统计#

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

/**
 * @author lymili
 * @Date 2022/4/1 16:51
 * @Version 1.0
 */
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        CountDifferentCharacterNumber res = new CountDifferentCharacterNumber();
        System.out.println(res.countDifferentCharacterNumber(str));
    }
}

class CountDifferentCharacterNumber {
    public int countDifferentCharacterNumber(String str) {
        Set<Character> charSet = new HashSet<>();
        for (int i = 0; i < str.length(); i++) {
            charSet.add(str.charAt(i));
        }
        return charSet.size();
    }
}