static void Main(string[] args)
{
StockController controller = new StockController();
TimeSpan workDay = new TimeSpan(0, 0, 2);
Task t1 = Task.Run(() => new SalesPerson("Pratik").Work(controller, workDay));
Task t2 = Task.Run(() => new SalesPerson("Varun").Work(controller, workDay));
Task t3 = Task.Run(() => new SalesPerson("Pradeep").Work(controller, workDay));
Task t4 = Task.Run(() => new SalesPerson("Himanshu").Work(controller, workDay));
Task.WaitAll(t1, t2, t3, t4);
controller.DisplayStatus();
Console.ReadLine();
}