class Student {
constructor(name, roll) {
  this.name = name;
  this.roll = roll;
}

study() {
  console.log(`${this.name} is studying`);
}
}

const student1 = new Student("Ripan", 101);
student1.study(); // Ripon is studying

class Animal {
speak() {
  console.log("Animal makes sound");
}
}

class Dog extends Animal {
speak() {
  console.log("Dog says: Woof Woof");
}
}

const myDog = new Dog();
myDog.speak(); // Dog says: Woof Woof

class BankAccount {
#balance; // private field

constructor(balance) {
  this.#balance = balance;
}

deposit(amount) {
  if (amount > 0) this.#balance += amount;
}

getBalance() {
  return this.#balance;
}
}

const account = new BankAccount(5000);
account.deposit(1000);
console.log(account.getBalance()); // 6000

class Bird {
sound() {
  console.log("Bird makes sound");
}
}

class Parrot extends Bird {
sound() {
  console.log("Parrot says: Hello!");
}
}

class Crow extends Bird {
sound() {
  console.log("Crow says: Caw Caw!");
}
}

const parrot = new Parrot();
const crow = new Crow();

parrot.sound(); // Parrot says: Hello!
crow.sound();   // Crow says: Caw Caw!

class Car {
constructor(model, color) {
  this.model = model;
  this.color = color;
}

rent() {
  console.log(`${this.model} has been rented`);
}

returnCar() {
  console.log(`${this.model} has been returned`);
}
}

const car1 = new Car("Toyota", "Red");
car1.rent();      // Toyota has been rented
car1.returnCar(); // Toyota has been returned