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

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        scanner.close();//关闭scanner,释放空间
        HashSet<Character> hs = new HashSet<>();

        //需求:从键盘获取一串字符串,要求去除重复的字符。请使用HashSet解决这一问题
        
        //先遍历字符串
        for(int i=0;i<str.length();i++){
            //添加到HashSet集合中去
            hs.add(str.charAt(i));
        }
        

        for (char c:hs) {
            System.out.print(c);
        }
    }
}