题解 | #提取不重复的整数#

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) {

        Scanner in = new Scanner(System.in);
//        String line1 = in.nextLine();
        String line = in.nextLine();
        char[] chars = line.toCharArray();
        //set 不重复集合
        Set<Character> set = new LinkedHashSet<>();

        for (int i = chars.length - 1; i >= 0; i--) {

            if (!(set.contains(chars[i]))) {
                set.add(chars[i]);

            }

        }
        Iterator<Character> iterator = set.iterator();
        while (iterator.hasNext()) {
            System.out.print(iterator.next());
        }


    }

}