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 can I help you at this moment? 
 customer: I am Alexander Mitchell here. I need to cancel my existing reservation, which is done recently. Can you please hep me out? 
 agent: Sure. I will help you with that. Please wait a moment. 
 customer: Thank you for considering my request. 
 agent: There is no previous reservation available under your name. 
 customer: Not a big problem, anyway thank you for the information. 
 agent: Thank you for reaching us. 
 customer: Thank you for searching.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
no_reservation