Given the task definition and input, reply with output. 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

customer: Hello. 
 agent: Hello, how may I assist you today? 
 customer: I want to cancel my reservation, can you help me with that? 
 agent: Sure, may I know your name for the cancellation process? 
 customer: Andrew Lee here. 
 agent: Thank you, please wait for a while. 
 customer: Sure. 
 agent:  Sorry, we couldn't find a reservation on your name to cancel. 
 customer: No problem, thank you for the information. 
 agent: Welcome, thank you for reaching us.

no_reservation