import java.util.*;

//从末尾遍历,去重放进list
public class Main{
    public static void  main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int indata = scanner.nextInt();
        String indataStr = indata + "";
        List<Character> outdataList  = new ArrayList<Character>();
        for(int i = indataStr.length()-1; i>=0 ;i--){
           //查找相同的字符
            if(!outdataList.contains(indataStr.charAt(i))){
                 outdataList.add(indataStr.charAt(i));
              }
        }
       //遍历list
        for(Character num : outdataList){
            System.out.print(Integer.parseInt(num + ""));
        }
    }
}