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. 
 agent: Hello, how can I help you? 
 customer: I am planning to visit Denver, will you help me in booking the flight ticket from JFK to DEN? 
 agent: May I know your desired travel dates please? 
 customer: My travelling dates are Apr 12 and Apr 14. 
 agent: May I know your name please? 
 customer: Myself Jack Robinson. 
 agent: Can I know your connection limit please? 
 customer: I need a connecting flight. 
 agent: Sorry to say, there is no flight on your desired travel dates. 
 customer: Can you please check with my  depart time it must be in morning. 
 agent: There is no flight on your preferred travel dates. 
 customer: Ok, not an issue. Thank you for your information. 
 agent: Thank you for opting us.
no_flight