import java.io.File;
import java.io.FilenameFilter;

public class HW01_1 {
    public static void main(String [] args)
    {
        if(args.length != 0)
        {
            File file1 = new File (args[0]);
            File [] files = null;

            if(file1.isDirectory())
                files = file1.listFiles(new DirFilter(".txt"));

            long length=0;

            if(files != null)
            {
                for(File file2 : files)
                    length += file2.length();
            }

            System.out.println(length/ files.length);
        }
    }
}
class DirFilter implements FilenameFilter
{
    private String check;

    DirFilter(String check) {
        this.check = check;
    }
    @Override
    public boolean accept(File dir, String name) {
        String tmp = new File(name).getName();
        return tmp.endsWith(check);
    }
}

import java.io.*;
import java.nio.charset.StandardCharsets;

public class HW01_2 {
    public static void main(String[] args) {
        try
        {
            File src = new File("source.txt");
            String text;

            if(!src.exists())
            {
                BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
                text = bf.readLine();

                PrintWriter pw = new PrintWriter("source.txt");
                pw.println(text);
                pw.close();
            }



            File dest = new File("destination.txt");
            FileInputStream input = new FileInputStream(src);

            RandomAccessFile dest2 = new RandomAccessFile(dest, "rw");
            dest2.setLength(src.length());

            long position = src.length();

            int b;
            while((b = input.read()) != -1)
            {
                String s = Character.toString((char)b);

                byte [] buff = s.getBytes();
                position -= buff.length;
                dest2.seek(position);

                dest2.write(buff);
            }

            input.close();
            dest2.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }}