Teacher: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
Teacher: Now, understand the problem? Solve this instance: customer: Hello. 
 agent: Hello. How can I abet you? 
 customer: My name is Betty Harris. I want to do some changes in my existing reservation. Can you help me for that? 
 agent: Sure, I will help you. 
 customer: Thank you. 
 agent: Sorry, no reservation found on your name to change your reservation. 
 customer: That's ok, thank you for your information. 
 agent: Welcome, have a nice day.
Student:
no_reservation