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. 
 customer: I am jonathan Miller. 
 agent: How can I assist you? 
 customer: My trip has been cancelled? Could you cancel my reservation? 
 agent: Yes, sure. Give me a moment. 
 customer: Ok. 
 agent: Jonathan Miller there is no reservation as per your name. 
 customer: It's ok. Thank you for your service. 
 agent: Thank you for choosing us.
no_reservation