import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
            int in=sc.nextInt();
            LinkedHashSet<Character> set=new LinkedHashSet<Character>();
            String s=String.valueOf(in);
            for(int i=s.length()-1;i>=0;i--){
                char target=s.charAt(i);
                set.add(target);
            }
            set.forEach(x->System.out.print(x));
        }
        System.out.println();
    }
}