Customers arrive at the Post Office with an exponentially distributed arrival time with an average arrival time of 3 minutes. Currently, there is only one employee at the counter to serve customers who want to deal. The treatment time for each customer is scattered exponentially with an average treatment time of 5 minutes. Customers often complain about the relatively long waiting time. To improve the quality of service and customer needs, the Post Office management took action to review the performance of the current system and plan to increase the number of employees at the counter. The number of employees will only be increased if it can reduce customer waiting time and meet customer charters. The customer charter that has been set is "you will be treated within 5 minutes". Build a simulation model and give a recommendation to the Post Office management the number of employees at the appropriate counter to be implemented