Given the task definition and input, reply with output. In this task, you are given a conversation between a flight agent and the customer. You are given 4 options and you need to select the goal of the conversation. It is provided as part of customer's context, which has to be one of the following: `book`: Make a new reservation, `cancel`: Cancel an existing reservation, `no_flight`: No flight found for the customer's preference, `no_reservation`: No reservation / No change / No cancellation was made in the conversation, mostly enquiring details

customer: Hello, Pamela Baker here. 
 agent: Hello, how may I guide you? 
 customer: I would like to play poker at Las Vegas. Can you help me in booking a ticket from DCA to LAS? 
 agent: Sure, may I know your journey dates please? 
 customer: My planned journey dates are 12/17 and 12/19. 
 agent: Please wait a moment. 
 customer: Ok, take your time. 
 agent: Pamela, no flights has been found on your journey dates. 
 customer: Its ok, thank you for the information. 
 agent: Thank you for reaching us.

no_flight