/*  svuk002@ec.auckland.ac.nz
 *
 *
 */
 
import java.io.*;
import java.util.*;

public class ReplaceAnswer {

	private static String fileIn;	/* This is the input file */
	private static String fileOut;   /* This is the output file */
	private static boolean overwrite; /* True if we are overwriting fileIn */ 
	
	private static String[] oldWords; /* Words to be replaced */
	private static String[] newWords; /* Replacement words */
	
	public ReplaceAnswer () {
		/* Begin the main program loop */
		mainLoop ();
	}
	
	
	/* You need to complete this method.
	 *
	 */
	private void mainLoop () {
		try {
			BufferedReader br = new BufferedReader (new FileReader (fileIn));
			BufferedWriter bw = new BufferedWriter (new FileWriter (fileOut));
			
			String currLine;
			while ((currLine = br.readLine ()) != null) {
				String newLine = replace (currLine);
				bw.write (newLine + "\n");
			}
			
			br.close ();
			bw.close ();
			
			if (overwrite) {
				File in = new File (fileIn);
				File out = new File (fileOut);
				in.delete ();
				out.renameTo (in);
			}
		}
		catch (FileNotFoundException e) {
			e.printStackTrace ();
		}
		catch (IOException e) {
			e.printStackTrace ();
		}
	}
	
	
	/* You need to complete this method.
	 *
	 */
	private String replace (String line) {
		StringTokenizer st = new StringTokenizer (line);
		String toRet = "";
		while (st.hasMoreTokens ())
			toRet += getNewWord (st.nextToken ()) + " ";
		return toRet;
	}
	
	/* You don't have to modify method below.
	 * It gets the replacement word for the word passed as argument.
	 */
	private String getNewWord (String old) {
		for (int i = oldWords.length - 1; i > -1; i--)
			if (oldWords[i].equals (old))
				return newWords[i];
		return old;
	}
	
	/* You don't have to modify the main method */
	public static void main (String[] args) {
		if (checkArgs (args))
			new ReplaceAnswer ();
		else
			printUsage ();
	}
	
	/* You don't have to modify the method below.
	 * Its purpose is to ``parse'' the command--line arguments
	 * and set appropriate flags.
	 */
	public static boolean checkArgs (String[] args) {
		Vector oldW = new Vector ();
		Vector newW = new Vector ();
		try {
			int currArg = 0;
			fileIn = args[currArg++];
			if (args[currArg].charAt (0) == '-') {
				if (args[currArg].charAt(1) != 'o')
					throw new ArrayIndexOutOfBoundsException ();
				currArg++;
				fileOut = args[currArg++];
			}
			else {
				fileOut = fileIn + "temp";
				overwrite = true;
			}
			for (int i = currArg; i < args.length; i+=2) {
				oldW.add (args[i]);
				newW.add (args[i+1]);
			}
			
			oldWords = new String[oldW.size ()];
			newWords = new String[newW.size ()];
			for (int i = 0; i < newW.size (); i++) {
				oldWords[i] = (String)oldW.elementAt (i);
				newWords[i] = (String)newW.elementAt (i);
			}
		}
		catch (ArrayIndexOutOfBoundsException e) {
			/* Oops... */
			return false;
		}
		catch (StringIndexOutOfBoundsException e) {
			/* Oops... */
			return false;
		}
		return true;
	}
	
	/* You don't have to modify the method below.
	 * It's purpose is to print usage of the program,
	 * in case things go wrong.
	 */
	public static void printUsage () {
		String usage = "Usage: java Replace input_file [-o output_file] oldWord1 " +
			"newWord1 [oldWord2 newWord2 ...]";
		System.out.println (usage);
	}
}