class QuestionEight{
	static boolean isISBN(String s)
	{
		if(s.length()!=13)
		{
			return false;
		}

		char c = s.charAt(12);

		if(c!='x' && !Character.isDigit(c))
		{
			return false;
		}
		int numSeps =0;
		int numDigits=0;

		for(int i =0;i<12; i++)
		{
			c=s.charAt(i);
			if(Character.isDigit(c))
			{
				numDigits++;
			}
			else if(c== ' ' || c== '-')
				{
					numSeps++;
				}
		}
		return numDigits==9 && numSeps==3;
	}

	public static void main(String [] args){

		System.out.println("please enter the ISBN: ");
		String isbn = Console.readString();

			if(isISBN(isbn))
			{
				System.out.println("valid ISBN");
			}
			else
			{
				System.out.println("not valid");
			}
	}
}