Create: IllegalArgumentException.java, Main.java, PasswordChecker.java

Update: Main.java

Update: Company.java

Update: TaxSix.java

Create: Logger.java, SimpleLogger.java, SmartLogger.java, Main.java

Create: Account.java, CreditAccount.java, SimpleAccount.java, Main.java

Create: TaxDebMinCr.java, TaxSix.java, TaxSystem.java, Company.java, Main.java

Create: Main.java

Update: Book.java (public boolean isBig)