import java.io.*;
import java.util.*;

public class MergeFiles {
    public static void main (String[] args) {
	if (args.length != 3) {
	    System.out.println("usage: java Mergefiles file1 file2 file3");
	    return;
	}
	Scanner rd1 = null;
	Scanner rd2 = null;
	PrintWriter pw = null;
	try {
		String aLine1 = null;
		String aLine2 = null;
		rd1 = new Scanner(new File(args[0]));
		rd2 = new Scanner(new File(args[1]));
		pw = new PrintWriter(new File(args[2]));
		if (rd1.hasNextLine())
		    aLine1 = rd1.nextLine();
		if  (rd2.hasNextLine()) 
		    aLine2 = rd2.nextLine();
		while (aLine1 != null && aLine2 != null) {
		    if (aLine1.compareTo(aLine2) <= 0) {
			pw.println(aLine1);
			if (rd1.hasNextLine()) 
		    	    aLine1 = rd1.nextLine();
			else
			    aLine1 = null;
		    } else {
			pw.println(aLine2);
			if (rd2.hasNextLine())
			    aLine2 = rd2.nextLine();
			else
			    aLine2 = null;
		    }
		}
		if (aLine1 != null) {
		    pw.println(aLine1);
		    while (rd1.hasNextLine()) {
			aLine1 = rd1.nextLine();
			pw.println(aLine1);
		    }
		}
		if (aLine2 != null) {
		    pw.println(aLine2);
		    while (rd2.hasNextLine()) {
			aLine2 = rd2.nextLine();
			pw.println(aLine2);
		    }
		}
	} catch (FileNotFoundException e) {
		System.out.println(e.getMessage());
	} finally {
		if (rd1 != null)
		    rd1.close();
		if (rd2 != null)
		    rd2.close();
		if (pw != null)
		    pw.close();
	}
    }
}