How many employees are suitable for 18 chess rooms?

18 chess rooms need 1-2 managers to be responsible for the operation and management of the whole chess room, 1 cleaner to be responsible for the cleaning and hygiene of the chess room, and 1-2 security guards to ensure the safety of customers and employees. Each chess room needs 1-2 waiters, so the total number of waiters is 18-36. We also need a cashier to take charge of the cashier work in the chess room. To sum up, 18 chess and card rooms need about 2-4 employees.