Q: 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 serve you? 
 customer: I want to change my existing reservation. Could you help me with that? 
 agent: Sure, I will help you. Please send your travelling dates. 
 customer: Please check with this name Karen Thomas for my previous reservation. 
 agent: Sure. Sorry, there is no reservation available with your given name. 
 customer: That's ok, thank you. 
 agent: You are welcome, have a nice day.
A:
no_reservation