cars.rb

class Car
  attr_reader :num
  attr_reader :seats

  def initialize(num, seats)
    @num = num
    @seats = seats
  end
end

cars = [
  Car.new(3, 12),
  Car.new(4, 9),
  Car.new(1, 10),
  Car.new(2, 8),
  Car.new(5, 19)
]

input = gets.chomp.to_i
index = cars.find_index { |car| car.num == input }
car = cars[index]

p "Car has #{car.seats} seats"