/*****************************************************************
** FilterDuplicateWords - 
**
** (c) Scott MacKenzie, 2000                             
******************************************************************/
import java.io.*;
import java.util.*;

public class FilterDuplicateWords
{
   public static void main(String[] args) throws IOException
   {
      // prepare keyboard for input
      BufferedReader stdin =
            new BufferedReader(new InputStreamReader(System.in), 1);

      // prepare to extract words from a line
      StringTokenizer words;
      String line;
      String word;
      String oldWord = "";

      // process lines until 'null' (no more input)
      while ((line = stdin.readLine()) != null)
      {
         // prepare to tokenize line
         words = new StringTokenizer(line);

         // process words in line
         while (words.hasMoreTokens())
         {
            word = words.nextToken();
            boolean isAlphaWord = true;
            int i = 0;
            if (!oldWord.equals(word))
            {
               oldWord = word;
               System.out.println(word);
            }
         }
      } 
   }         
}