You will be given a definition of a task first, then some input of the task.
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 can I help you? 
 customer: My name is Ronald Martin. I need to book a flight ticket from ORD to DCA. Please help me in booking a flight ticket. 
 agent: Sure, I will help you with it. 
 customer: Thank you. 
 agent: May I know when are you willing to travel? 
 customer: My journey dates are from 12/06 to 12/08. 
 agent: Do you prefer a halt between your journey? 
 customer: Yes, I prefer a halt. 
 agent: Please let me know if you have any other preferences? 
 customer: No, I do not have any other preference. 
 agent: Please wait for a while. 
 customer: Sure. 
 agent: I am sorry to inform you that there is no flight available on given dates from you. 
 customer: No problem, thanks for your information. 
 agent: Thank you for reaching us, we hope to serve you better next time.
Output:
no_flight