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, Sharon Thompson here. 
 agent: Hello, how may I help you? 
 customer: I am planning to shoot a documentary to the famous places in Oakland, CA - OAK. Can you aid me for booking with a direct flight? 
 agent: Sure, can I have your trip dates? 
 customer: My trip dates are on 09/22 to 09/24. 
 agent: Help me with the source code? 
 customer: My source is Washington, DC - DCA. 
 agent: Sorry, we do not found any flights running in your given dates. 
 customer: That's Ok, thanks for your information. 
 agent: Thank you for your approach.
Output:
no_flight