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 aid you? 
 customer: I am George Moore. I had planned to go on a trip, but it was postponed. Can you change my recent reservation? 
 agent: Sure, I am happy to help you. Please wait, let me check your reservation status in our database. 
 customer: Ok, take your time. 
 agent: Sorry, there is no reservation under your name in our database. 
 customer: That's ok. Anyways, thank you for your help. 
 agent: You are welcome and have a nice day.
no_reservation