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 may I assist you? 
 customer: I am Laura Carter here, I want to reserve my ticket from BOS to PHL, can you please help me in booking? 
 agent: May I know your trip dates? 
 customer: Sure, my planned dates of journey are from Sep, 01 to Sep, 03. 
 agent: May I know your connection limit? 
 customer: Yes, I need a connecting flight. 
 agent: Is there any class preference? 
 customer: Yes, I need a business class. 
 agent: Ok, can you share your name to proceed further? 
 customer: I have mentioned. 
 agent: Ok, do you have any other specifications? 
 customer: No. 
 agent: Ok, please wait. 
 customer: Sure, I will wait. 
 agent: Sorry, there are no flights found with your required details. 
 customer: Ok, no problem. Anyways, thank you for your service. 
 agent: Thank you for reaching us.
Output:
no_flight