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 str = in.next();
        char[] array = str.toCharArray();
        LinkedHashSet<Character> set = new LinkedHashSet<>();

        for (int i = array.length - 1; i >= 0; i--) {
            set.add(array[i]);
        }

        for (Character c : set) {
            System.out.print(c);
        }
    }
}