Inheritance

using System;

// Base class
class Person
{
    // Fields
    private string firstName;
    private string lastName;
    private int age;

    // Constructor
    public Person(string firstName, string lastName, int age)
    {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }

    // Properties
    public string FirstName
    {
        get { return firstName; }
        set { firstName = value; }
    }

    public string LastName
    {
        get { return lastName; }
        set { lastName = value; }
    }

    public int Age
    {
        get { return age; }
        set
        {
            if (value >= 0)
                age = value;
            else
                throw new ArgumentOutOfRangeException("Age must be a positive number.");
        }
    }

    // Method
    public void DisplayDetails()
    {
        Console.WriteLine($"Name: {FirstName} {LastName}, Age: {Age}");
    }

    // Virtual method for overriding
    public virtual void PrintRole()
    {
        Console.WriteLine("Person's role: Unknown");
    }
}

// Derived class
class Student : Person
{
    // Additional property
    public string Major { get; set; }

    // Constructor
    public Student(string firstName, string lastName, int age, string major)
        : base(firstName, lastName, age)
    {
        Major = major;
    }

    // Method overriding
    public override void PrintRole()
    {
        Console.WriteLine("Person's role: Student");
    }

    // Method to display student details
    public void DisplayStudentDetails()
    {
        DisplayDetails();
        Console.WriteLine($"Major: {Major}");
    }
}

// Derived class
class Teacher : Person
{
    // Additional property
    public string Subject { get; set; }

    // Constructor
    public Teacher(string firstName, string lastName, int age, string subject)
        : base(firstName, lastName, age)
    {
        Subject = subject;
    }

    // Method overriding
    public override void PrintRole()
    {
        Console.WriteLine("Person's role: Teacher");
    }

    // Method to display teacher details
    public void DisplayTeacherDetails()
    {
        DisplayDetails();
        Console.WriteLine($"Subject: {Subject}");
    }
}

class Program
{
    static void Main()
    {
        // Creating an object of the Student class
        Student student = new Student("Priyanka", "Tiwari", 21, "Computer Science");
        student.DisplayStudentDetails();
        student.PrintRole();

        // Creating an object of the Teacher class
        Teacher teacher = new Teacher("Bob", "Smith", 46, "Mathematics");
        teacher.DisplayTeacherDetails();
        teacher.PrintRole();
    }
}