Library Management System

You are required to implement a library management system that supports various operations including adding users, adding books, borrowing books, returning books, and checking the status of a book. The operations will be provided via standard input with the following commands:

• ADD_USER user_id name: Add a new user.
• ADD_BOOK isbn title: Add a new book.
• BORROW_BOOK user_id isbn: Allow a user to borrow a book if it is available.
• RETURN_BOOK user_id isbn: Allow a user to return a book they have borrowed.
• BOOK_STATUS isbn: Check whether a book is available or borrowed. If borrowed, display the borrowing user's ID.

Note: The total number of commands is given by $Q$. Every operation that is expected to have an output (i.e. BORROW_BOOK, RETURN_BOOK, BOOK_STATUS) must print a message to standard output. The expected messages are:

• Book borrowed successfully
• Cannot borrow book
• Book returned successfully
• Cannot return book
• Book is available
• Book is borrowed by user user_id

Make sure to use LaTeX style formatting for any formulas such as $Q$, for example, $\text{command count} = Q$.

inputFormat

Input is given via standard input. The first line contains an integer $Q$ (the number of operations). Each of the following $Q$ lines contains a command in one of the following formats:

• ADD_USER user_id name • ADD_BOOK isbn title • BORROW_BOOK user_id isbn • RETURN_BOOK user_id isbn • BOOK_STATUS isbn

Note: All tokens are separated by spaces. The commands ADD_USER and ADD_BOOK do not produce any output.

outputFormat

For every command that produces output (i.e. BORROW_BOOK, RETURN_BOOK, BOOK_STATUS), print the corresponding message on a new line. The messages should exactly match one of the following:

• Book borrowed successfully • Cannot borrow book • Book returned successfully • Cannot return book • Book is available • Book is borrowed by user <user_id>## sample

6
ADD_USER 1 Alice
ADD_BOOK 123456 The_Great_Gatsby
BORROW_BOOK 1 123456
BOOK_STATUS 123456
RETURN_BOOK 1 123456
BOOK_STATUS 123456

Book borrowed successfully
Book is borrowed by user 1
Book returned successfully
Book is available

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