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 Eric Carter. 
 agent: Hello, how may I aid you? 
 customer: Due to sudden changes, my exams has been postponed. Can you please change my reservation? 
 agent: sure, we are perky to help you. 
 customer: Thank you. 
 agent: Please wait for a while. 
 customer: Ok. 
 agent: There is no active reservation found on your name in our database. 
 customer: Ok, not an issue. Thank you for your information. 
 agent: Thank you for choosing us.
Output:
no_reservation