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,. I am Betty Anderson. 
 agent: Hello, how may I aid you today? 
 customer: Can you please book a flight ticket with direct flight to attend a event in San Francisco? 
 agent: Sure, help me with the trip dates? 
 customer: My journey dates are on Jan 27th and 29th. 
 agent: Do you have any preferences? 
 customer: My return flight time should be in the evening. 
 agent: May I know your airport codes? 
 customer: My airport codes are, OAK to SFO. 
 agent: Thank you for your details, we do not found any flights running in your desired routes. 
 customer: Ok, no problem. Thank you. 
 agent: Thank you for reaching us.
Output:
no_flight