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. 
 customer: My name is Larry Wilson. 
 agent: How can I help you today? 
 customer: I have a plan to meet my friend in Oakland, can you help me for booking a flight ticket? 
 agent: Sure, I will help you in booking. Can you please share your travel dates? 
 customer: My travelling dates are from 09/02 till 09/04. 
 agent: Ok, may I know your airport codes? 
 customer: My travelling airport codes are from DTW to OAK. 
 agent: Sorry, no flights are available on your route. 
 customer: That's ok, thank you for checking. 
 agent: Welcome, have a nice day.
Output:
no_flight