Definition: 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
Input: customer: Hello. 
 agent: Hello. How may I assist you at this moment? 
 customer: Myself Sandra Phillips. Can you please book a flight ticket from SFO to LGA? 
 agent: Sure, may I know your planned dates of travelling? 
 customer: Sure, I need to travel on dates of 04/05 and 04/07. 
 agent: Please wait a moment to check the flights availability. 
 customer: Sure, take your time. 
 agent: Sorry to inform you that, there are no flights moving to your region with your planned dates of travelling. 
 customer: Oh! It is sad to hear. Anyway, I will go  with another agency this time. 
 agent: Thank you for approaching us, have a great day. 
 customer: Thank you for your time. 
 agent: Welcome.
Output:
no_flight