You will be given a definition of a task first, then some input of the task.
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. I am Carol Phillips. 
 agent: Hello, what can I do for you to make you happy? 
 customer: I made a reservation earlier in the wrong date unknowingly so, I want to change my existing reservation. So please help me in cancellation. 
 agent: Sure, please be on hold. 
 customer: Ok. 
 agent: Thanks for your time, we found a reservation on your name and it has been cancelled successfully. 
 customer: Thank you. 
 agent: Thanks for contacting us.
Output:
cancel