static void Main(string[] args)
{
Employee e = new Employee(300, "nguyen", "minh", 1500000);
Console.WriteLine(e.toString());
e.setSalary(3000000);
Console.WriteLine("id " + e.getID() + " firstName " + e.getFirstName() + " lastName " + e.getLastName() + " salary " + e.getSalary());
Console.WriteLine(e.toString());
Console.WriteLine(e.getAnnualSalary());
Console.WriteLine(e.raiseSalary(10 / 100));
}