题解 | 最小循环节

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 str = in.next();
        Set<Character> set = new HashSet<>();
        int len = str.length();
        for(int i = 0;i<len;i++){
            char c = str.charAt(i);
            set.add(c);
        }
        System.out.println(set.size());
    }
}