/*
When run, this program opens the specified file, prints out it's contents, and then 
writes them back to the same file in reverse order (last line first)
*/
import java.io.*;
import java.util.*;

public class InputOutput
{
  ArrayList<String> contents;
  
  public InputOutput()
  {
    contents=new ArrayList<String>();
  }
  
  public static void main(String[] args)
  {
    if(args.length!=1)
    {
      System.err.println("Usage: InputOutput fileName");
      return;
    }
    InputOutput io=new InputOutput();
    if(!io.readFile(args[0])) return;
    io.printContents();
    if(!io.writeFile(args[0])) return;
  }
  
  public boolean readFile(String fname)
  {
    try
    {
      BufferedReader br=new BufferedReader(new FileReader(fname));
      String s=br.readLine();
      while(s!=null)
      {
        contents.add(s);
        s=br.readLine();
      }
      br.close();
    }
    catch(Exception e)
    {
      System.err.println("Error reading file '"+fname+"': "+e);
      return false;
    }
    return true;
  }
  
  public void printContents()
  {
    for(int i=0;i<contents.size();i++) System.out.println(contents.get(i));
  }
  
  public boolean writeFile(String fname)
  {
    try
    {
      BufferedWriter bw=new BufferedWriter(new FileWriter(new File(fname)));
      for(int i=contents.size()-1;i>=0;i--)
      {
        bw.write(contents.get(i));
        bw.newLine();
      }
      bw.close();
    }
    catch(Exception e)
    {
      System.err.println("Error writing file '"+fname+"': "+e);
      return false;
    }
    return true;
  }
}