题解 | #提取不重复的整数#

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

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int a = in.nextInt();
        HashSet<Integer> set = new HashSet<>();
        while(a != 0){
        	int b = a % 10;
        	if(set.add(b)){
        		System.out.print(b);
        	}
        	a /= 10;
        }
        
        
        in.close();
    }
}