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. Myself Linda Davis. 
 agent: Hello, how may I help you today? 
 customer: I need to change my existing reservation, can you please help me? 
 agent: Sure, I will help you with that. Please wait for a moment. 
 customer: Sure. 
 agent: Thanks for waiting, no active reservation was found on your name in the database. 
 customer: That's ok, thank you for searching my details. 
 agent: Thank you for choosing us.
Output:
no_reservation