You will be given a definition of a task first, then some input of the task.
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 may I assist you today? 
 customer: Can you please help me in booking a flight ticket from DEN to DTW? 
 agent: Sure, may I know your planned trip dates? 
 customer: I would like to fly on Nov 16 and return on Nov 18. 
 agent: Do you have any connection limit? 
 customer: I need a single connection. 
 agent: Any other requirements to be met? 
 customer: I would like to return in the morning time. 
 agent: May I know your good name? 
 customer: Myself David Jones. 
 agent: Sorry, there are no flights found with your given details. 
 customer: Not an issue. Thank you. 
 agent: Thank you for reaching us.
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
no_flight