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 Jacob Green. 
 agent: Hello, how can I help you today? 
 customer: I want to change my reservation, can you please help me? 
 agent: Sure, please wait for a moment. 
 customer: Sure. 
 agent: Sorry to say that, no reservation was found with your good name. 
 customer: Ok, not a problem. Thank you. 
 agent: Thank you for reaching us.
Output:
no_reservation