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. 
 agent: Hello, how can I assist you today? 
 customer: I want to change an existing reservation, so please help me in changing the reservation. 
 agent: Sure, I am glad to help you. 
 customer: Ok. 
 agent: May I know your name please? 
 customer: Myself Justin Taylor. 
 agent: Ok, please wait for a while. 
 customer: Ok. 
 agent: Sorry to say that, no reservation was found on your name to change. 
 customer: Not an issue. Thank you. 
 agent: Thank you for choosing us.
Output:
no_reservation