READ ME: The code is used to simulate the logic for bank waitting list. Requirements: 1. There are 6 service windows. Common Service Window: 1 - 4 Express Service Window: 5 VIP Window: 6 2. There are 3 kinds of customers. Common Customer Express Customer VIP Customer 3. The rates of different kinds of customers. VIP Customer : Common Customer : Express Customer = 1 : 6 : 2 4. There are Max time and Min time for the agent to complete the customer’s business. 5. Common customer is serviced in the common service window. Express customer is serviced in the express service window. VIP customer is serviced in the VIP window. 6. The bank tellers in the VIP and Express window could service the common customers if they do not have the express customers and VIP customers to service.