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. I am Emily Evans. 
 agent: Hello, how may I assist you? 
 customer: I am planning to travel from PHL to EWR. Can you please help me to book a ticket? 
 agent: Sure, we are here to help you. May I know your travel dates? 
 customer: My travelling dates will be on 07/16 to 07/18. 
 agent: Ok, please wait a moment. 
 customer: Ok. 
 agent: Sorry, there were no flights found on your route. 
 customer: Ok, not an issue. Thank you for your information. 
 agent: Thank you for reaching us.
Output:
no_flight