Add to your C pgm of Lab 4 as follows: Declare the following operator overloads in your 'book. h' as class member methods: Assignment operator which will copy one Book object to another book object. operator to cast to an integer - return the ISBN number in such an operation. Comparison (is equal to) operator to compare two book objects. Declare the following operator overloads in your 'book. h' as friend methods: input stream operator to get input. output stream operator to write object data to output. Define the code for all the 5 operators above in your 'book. cpp' file. Declare the destructor. Now modify your main in 'bookmain. cpp' such that first 50% of the books are read from the input file using the input stream operator overload and written to the screen as in Lab 4.