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: Hi. I am Karen Walker. 
 agent: Hello, how can I be your helping hand today? 
 customer: Can you help me in cancelling my recent reservation, as my exam is postponed? 
 agent: Sure, we will help you. Please wait for a minute. 
 customer: Sure. 
 agent: Thanks for your time, no reservation was found on your name to cancel. 
 customer: That's ok, thank you. 
 agent: Thank you for reaching us. We hope to serve you again.
no_reservation