import java.util.NoSuchElementException;
import java.util.Scanner;
import java.util.Stack;

/**
* A Class to use stacks to determine if a string is a palindrome
* This downcases the text and removes spaces.  
* It also removes most punctuation
*/
public class Palindromer
{
	public boolean palCheck(String pal) {
		pal = pal.toLowerCase().replace(" ", "").replace(".", "").replace(",","").replace(";","").replace("?","").replace("!","");
		// really want char in stack, but it is primitive type
		// so use Character  similar to int/Integer
		Stack<Character> aSStr = new Stack<>(); 
		int middle = pal.length()/2;
		// first push onto stack the characters up to the middle of the string
		for (int i=0; i<middle; i++)
		{
			aSStr.push(pal.charAt(i)); // note autoboxing
		}
		// if the string has an odd length, skip the middle character
		if (pal.length()%2 == 1)
		{
			middle++;
		}
		boolean good = true; // start by assuming that the string is a palindrome
		
		// from the middle to the end, compare the current char to the one popped off the stack.
		for (int i=middle; i<pal.length(); i++)
		{
			Character fromStack = aSStr.pop();
			char fromString = pal.charAt(i);
			if (fromStack==null || fromStack!=fromString)  // note autounboxing
			{
				good = false;
				break;
			}
		}
		return good;
	}	
	
	public static void main(String[] args)
	{
		Palindromer pdrome = new Palindromer();
		
		try ( Scanner br = new Scanner(System.in);) {
			while (true)
			{
				System.out.println("Enter string to check for Palindrome");
				String pal="";
				try {
					pal = br.nextLine();
					if (pal.length() == 0) {
						System.out.println("Have a nice day");
						return;
					}
					boolean isPal = pdrome.palCheck(pal);
					if (isPal) {
						System.out.println("Good");
					} else {
						System.out.println("Bad");
					}
				} catch (NoSuchElementException nsee) {
					System.err.println(nsee);
					return; // just quit in the face of this exception
				} catch (IllegalStateException ise) {
					System.err.println(ise);
					return; // just quit in the face of this exception, also
				}
			}
		} finally {}
	}
}