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, I am Edward Thompson. 
 agent: Hello, How can I assist you? 
 customer: I am planning for a holiday vacation at Boston, can you please book a flight ticket? 
 agent: Sure, May I know the travel date details? 
 customer: I want to travel on 04/06 and arrival is on 04/08. I do not need connections in between my journey. 
 agent: May I know the source and destination details? 
 customer: My journey starts from Oakland, CA-OAK to Boston, MA-BOS. 
 agent: Sorry, There is no direct flight. Thank you for availing us. 
 customer: Thank you.

no_flight