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 best help you? 
 customer: I am Stephen Roberts want to travel to CA-SFO to meet my brother. Can you book a connecting flight? 
 agent: Sure, may I know your travelling dates? 
 customer: My travelling dates are 12/10 and 12/12. 
 agent: Is there any restrictions in ticket fare? 
 customer: I can afford up to 5000. 
 agent: May I know from where you are flying from? 
 customer: I will depart from NV-LAS. 
 agent: Ok, please wait for a while. 
 customer: Ok. 
 agent: There is a flight found with JetBlue airline of flight number 1009 and fare is 100. Shall I proceed for booking? 
 customer: Ok, you can proceed. 
 agent: Your ticket has been confirmed. 
 customer:  Thank you for booking. 
 agent: Thanks for contacting us.have a nice journey.
book