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, how may I help you? 
 customer: Can you please check a flight from DTW to JFK? 
 agent: Sure, we are glad to assist you. 
 customer: Thank you. 
 agent: On which dates would you like me to book a flight ticket for you? 
 customer: I will fly on May 1st and intend to return on May 3rd. 
 agent: Would you like to travel in economy or business class? 
 customer: I am comfortable to travel in any class. 
 agent: May I know your good name? 
 customer: I am Carol Miller. 
 agent: Help me with your connection limit? 
 customer: Sure, I need a connecting flight. 
 agent: Please, wait. 
 customer: Sure. 
 agent: Thank you for waiting, sorry there is no flight available on your journey data. 
 customer: No problem, thanks for your information. 
 agent: Thank you for reaching us.
no_flight