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 help you? 
 customer: I want to cancel my recent reservation due to sudden postpone of my exams. Can you help me with that? 
 agent: Sure, I will help you. 
 customer: Thank you. 
 agent: May I know your name? 
 customer: I am Emma Moore. 
 agent: Please wait for a while. 
 customer: Sure. 
 agent: Sorry, there are no reservation found on your name. 
 customer: Ok, no problem. Thank you. 
 agent: Thank you for choosing us.
Student:
no_reservation