$3.$Case study: Suppose you are tasked with designing a program to manage company employees. The requirements include defining different types of employees, such as fulltime, part$-$time, and contractual, each with specific attributes and behaviors. Implement the necessary structures, interfaces, abstract classes, and inheritance to fulfill these requirements. $3\mathrm{.}1$ a$).$ Define a structure named "Address" with the following fields:

string Street

string City

string State

int ZipCode

b$).$ Define an interface named IEmployee with the following methods:

void DisplayDetails$0$: This method should display the employee's details.

double CalculateSalary$0$: This method should calculate and return the employee's salary.

c$).$ Define an abstract class named Employee that implements the IEmployee interface and has the following properties and methods:

Properties:

int Employeeld

string FullName

Address EmployeeAddress

Methods:

abstract double CalculateSalary$()$: This method should be implemented by derived

classes to calculate the salary of specific types of employees.

Virtual void DisplayDetails$()$: This method should display the employee's details.

$(25$marks$)$

NOTE: code in C#