import java.io.*;

/**
 * CatFile
 */
public class CatFile{
    public CatFile(String file1, String file2, String dst_file){
	try{
	    DataInputStream  in = new DataInputStream(new FileInputStream(file1));
	    DataOutputStream out= new DataOutputStream(new FileOutputStream(dst_file));
	    int b= in.read();
	    while(b!=-1){
		out.write(b);
		b= in.read();
	    }
	    in.close();

	    in = new DataInputStream(new FileInputStream(file2));
	    b= in.read();
	    while(b!=-1){
		out.write(b);
		b= in.read();
	    }
	    in.close();


	    out.close();
	}catch(IOException e){
	    e.printStackTrace();
	}
    }

    /**
     * main
     */
    public static void main(String[] args){
	if(args.length!=3){
	    System.err.println("usage : java CatFile <file1> <file2> <dst_file>");
	}else{
	    new CatFile(args[0], args[1], args[2]);
	}
    }
}