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();
HashSet<Character> hs = new HashSet<>();
for (int i=0;i<str.length();i++)
{
hs.add(str.charAt(i));
}
for (char c:hs) {
System.out.print(c);
}
}
}