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 Betty Campbell. 
 agent:  Hello, How exactly I can serve you the best today? 
 customer: Can you help me to book a direct flight from LGA - OAK? 
 agent: Sure, I will help you with that. 
 customer: Thanks. 
 agent: Kindly, mention your travelling dates? 
 customer: My travelling dates are 07/26 and 07/28. 
 agent:  Ok, please wait a moment, let me search a flight for you. 
 customer: Sure. 
 agent: Sorry to inform you, currently no flights are running at that locations due to abnormal weather conditions. 
 customer: Ok, no issues. Thank you. 
 agent: Thank you for choosing us.
no_flight