Exercise $3$: Abstract Classes

Task: Create an abstract class Employee with a method calculateSalary$().$ Extend this class with

two subclasses: Manager and Developer. Implement the calculateSalary $()$ method in each subclass

with different formulas. Create instances of both subclasses and calculate their salaries.

Instructions: After implementing the solution, draw a class diagram representing the classes Employee,

Manager, and Developer. Include associations and any relevant attributes or methods.