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. 
 agent: Hello. How can I help you? 
 customer: Jennifer Mitchell here. Owing an emergency, I want to cancel my recent reservation. Can you please help me? 
 agent: Sure, I will help you to cancel your reservation. 
 customer: Thank you. 
 agent: I found your reservation and it is successfully cancelled. 
 customer: Thank you for the help in cancelling my ticket. 
 agent: Welcome.

cancel