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 may I aid you? 
 customer: I want to attend for an interview in New York, so please book a flight ticket from PHL to EWR. 
 agent: Sure, may I know your itinerary dates? 
 customer: I want to fly on Dec 10, return on Dec 12. 
 agent: Do you prefer a direct or connecting flight? 
 customer: I need a connecting flight. 
 agent: Do you have any specifications? 
 customer: No. 
 agent: May I know your name? 
 customer: My name is Nicole Johnson. 
 agent: Sorry Nicole Johnson, no flights are available on your route. 
 customer: No problem, thank you. 
 agent: Thank you for reaching us.
no_flight