//เฉลยช้อสอบOOPตัดคำซ้ำ
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class NewMain {

    public static void main(String[] args) {
           ArrayList<String> word = new ArrayList<String>();
           ArrayList<String> resul = new ArrayList<String>();
           Scanner Sc = new Scanner(System.in);
           String s;
           s=Sc.next();
           while(true)
           {
               word.add(s);
               s=Sc.next();
               if(s.equals("-1"))
                   break;
           }

             int temp = 0;
             resul.add(word.get(0));
           for(int i = 0 ; i < word.size(); i++){
               if(!word.get(i).equals(resul.get(temp))){
                   resul.add(word.get(i));
                   temp++;
               }




           }
           for(int i = 0 ; i < resul.size(); i++){
               System.err.println(resul.get(i));
           }

    }

}