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. 
 customer: I am Brenda Gonzalez. 
 agent: How may I assist you at this moment? 
 customer: Owing to an emergency, I want to cancel my recent reservation. Can you help me out? 
 agent: Sure, I am glad to help you with that. Please be on hold to check your previous reservation. 
 customer: Ok, take your time. 
 agent: As per your request, I have successfully cancelled your reservation. 
 customer: Thank you for your help. 
 agent: Thank you for approaching us, have a great day.
cancel