Instructions: 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
Input: customer: Hello. 
 agent: Hello. 
 customer: I am Robert Collins. 
 agent: How can I useful to you? 
 customer: Can you help me in changing reservation? 
 agent: Sure, I am perky to help you. 
 customer: Thank you. 
 agent: Please wait for some time. 
 customer: Sure. 
 agent: Thanks for waiting. 
 customer: Ok. 
 agent: Sorry to inform you Robert, there is no reservation found with your name in our records. 
 customer: Ok, No issues. Thank you. 
 agent: Thank you for choosing us, have a good day.
Output:
no_reservation