题解 | 最小循环节 - set 计数

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

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.nextLine().trim();
        Set<Character> set = new HashSet<>();
        for(char ch : s.toCharArray()) set.add(ch);
        System.out.println(set.size());
    }
}