A palindrome is a string that reads the same in both directions. For example, the word racecar is a palindrome but alabama is not (reverse amabala). To make it more fun, we define a palindrome to be case and punctuation insensitive. That is, the string Race car! is also considered a palindrome.

Here comes a long one: A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal--Panama! (discovered by Guy Jacobson), and an even longer one: A man, a plan, a canoe, pasta, heros, rajahs, a coloratura, maps, snipe, percale, macaroni, a gag, a banana bag, a tan, a tag, a banana bag again (or a camel), a crepe, pins, Spam, a rut, a Rolo, cash, a jar, sore hats, a peon, a canal--Panama! (discovered by Guy Steele).

As the length grows, it is difficult to check if a string is indeed a palindrome. In this exercise, we are going to implement a Java program to do this job.

Download skeleton code and follow instructions here to build a Java project.

Two files are contained in the package: PalindromeDetector.java and PalindromeDetectorDriver.java. The driver program PalindromeDetectorDriver handles file I/O: it iteratively reads a line from an input file and writes it to the output file only if the line is detected as a palindrome. You need to implement the isPalindrome method of PalindromeDetector, which takes a string as input and returns true if the string is a palindrome and false otherwise.

A string is defined as a palindrome if, after removing all non-letter characters (characters other than a-z and A-Z) and converting all letters to lower case, it reads identical in both directions.

Example

Input file:

This line, and the two lines below, shouldn't appear in output!
Below is a list of palindromes from
http://en.wikipedia.org/wiki/Palindrome
racecar
Dammit, I'm mad!
If I had a hi-fi
Madam, I'm Adam
Madam, in Eden, I'm Adam
War, sir, is raw
Yo, banana boy!
Do geese see God?
Rise to vote, sir
Was it a cat I saw?
Was it a car or a cat I saw?
Never odd or even
No devil lived on
A Toyota's a Toyota
No lemons, no melon
Now I see bees, I won
Race fast, safe car
Ah, Satan sees Natasha
A dog, a panic in a pagoda
Ma is as selfless as I am
Nurse, I spy gypsies-run!
A man, a plan, a canal: Panama
A dog, a plan, a canal, pagoda
Was it Eliot's toilet I saw?
No, sir, away! A papaya war is on!
Go hang a salami, I'm a lasagna hog
I, madam, I made radio! So I dared! Am I mad? Am I?
Taco Cat
Swap God for a janitor, rot in a jar of dog paws.
Mr. Owl ate my metal worm.
Rats live on no evil star.
Eva, can I see bees in a cave?
Step on no pets.
    

Output file:

racecar
Dammit, I'm mad!
If I had a hi-fi
Madam, I'm Adam
Madam, in Eden, I'm Adam
War, sir, is raw
Yo, banana boy!
Do geese see God?
Rise to vote, sir
Was it a cat I saw?
Was it a car or a cat I saw?
Never odd or even
No devil lived on
A Toyota's a Toyota
No lemons, no melon
Now I see bees, I won
Race fast, safe car
Ah, Satan sees Natasha
A dog, a panic in a pagoda
Ma is as selfless as I am
Nurse, I spy gypsies-run!
A man, a plan, a canal: Panama
A dog, a plan, a canal, pagoda
Was it Eliot's toilet I saw?
No, sir, away! A papaya war is on!
Go hang a salami, I'm a lasagna hog
I, madam, I made radio! So I dared! Am I mad? Am I?
Taco Cat
Swap God for a janitor, rot in a jar of dog paws.
Mr. Owl ate my metal worm.
Rats live on no evil star.
Eva, can I see bees in a cave?
Step on no pets.

    

Sample solution