import java.util.*;
public class Main{
public static void main(String []args){
LinkedHashSet<String>lset=new LinkedHashSet<String>();
Scanner sc=new Scanner(System.in);
String str=sc.nextLine();
for(int i=0;i<str.length();++i){
lset.add(String.valueOf(str.charAt(i)));
}
//String str1 = null;
StringBuilder stb=new StringBuilder();
for(String str2:lset){
stb.append(str2);
//System.out.println(str2);
}
System.out.println(stb.toString());
}
}