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: Hello. 
 agent: Hello. 
 customer: I am Michelle Martinez. 
 agent: Martinez, how may I assist you today? 
 customer: I want to visit Seattle, can you help me in booking a ticket? 
 agent: Sure, I will help you, may I know your airport codes? 
 customer: My airport codes are from CLT to SEA. 
 agent: When you are going to start your journey? 
 customer: I want to start my journey on 12/26 and return on 12/28. 
 agent: Ok, wait for a moment please. 
 customer: Ok. 
 agent: Sorry to say this, no flights as per your details. 
 customer: No problem, thank you for checking. 
 agent: It is my pleasure, have a nice day.
Output:
no_flight