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: Hi. 
 agent: Hello. 
 customer: I am Samuel Green. 
 agent: How may I guide you today? 
 customer: I want to book a ticket from LGA to MSP, for attending a birthday party of my friend. 
 agent: Sure, I will help you with that. 
 customer: Thank you. 
 agent: Can  you please share your journey dates? 
 customer: Sure, my travelling dates are 11/16 and 11/18. 
 agent: Wait for a minute. 
 customer: Sure. 
 agent: I am sorry to say that there is no flight found. 
 customer: It's ok, thanks for your information. 
 agent: Thank you for contacting us.
no_flight