// ------------------------------------------------------
// Using Directives
// ------------------------------------------------------

using System.Collections.Generic;
using System.IO;
using System;

// ------------------------------------------------------
// Palindrome
// ------------------------------------------------------

public class Palindrome
{
   // ------------------------------------------------------
   // GetWords - Returns false if 'fileName' could not be
   //            read and populates 'errMsg', returns true
   //            otherwise and populates 'words'
   // ------------------------------------------------------

   public static bool GetWords(
      string fileName, out string[] words, out string errMsg
   )
   {
      words  = null;
      errMsg = null;

      try
      {
         words = File.ReadAllLines(fileName);
      }
      catch(Exception e)
      {
         errMsg = e.Message;
         return(false);
      }

      return(true);
   }

   // ------------------------------------------------------
   // ArePalindrome - Returns true if word1 + word2 makes
   //                 a palindrome, false otherwise
   // ------------------------------------------------------

   public static bool ArePalindrome(string word1, string word2)
   {
      if(string.IsNullOrEmpty(word1) || string.IsNullOrEmpty(word2))
         return(false);

      string s1 = word1;
      string s2 = word2;

      int n1 = word1.Length;
      int n2 = word2.Length;

      int index1 = 0;
      int index2 = n2 - 1;

      for(int i = 0, n = (n1 + n2) / 2; i < n; i ++)
      {
         if(s1[index1] != s2[index2])
            return(false);

         if(++index1 == n1)
         {
            s1     = word2;
            index1 = 0;
         }

         if(--index2 < 0)
         {
            s2     = word1;
            index2 = n1 - 1;
         }
      }

      return(true);
   }

   // ------------------------------------------------------
   // ShowWords - Output the contents of 'words'
   //             to the console
   // ------------------------------------------------------

   public static void ShowWords(string[] words)
   {
      foreach(string word in words)
         Console.WriteLine("'{0}'", word);
   }

   // ------------------------------------------------------
   // Main
   // ------------------------------------------------------

   public static void Main()
   {
      string errMsg;
      string[] words;

      if(!GetWords("words.txt", out words, out errMsg))
      {
         Console.WriteLine(errMsg);
      }
      else
      {
         //ShowWords(words);

         for(int i = 0; i < words.Length; i ++)
         {
            for(int j = 0; j < words.Length; j ++)
            {
               if(i != j)
               {
                  if(ArePalindrome(words[i], words[j]))
                     Console.WriteLine("'{0}' + '{1}'", words[i], words[j]);
               }
            }
         }
      }

      Console.Read();
   }
}