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. How may I guide you? 
 customer: Can you please help me to change my reservation? 
 agent: Sure, I will help you. On which name you have reserved your previous reservation? 
 customer: My name is Ashley Lewis. 
 agent: Ok, please wait a minute. 
 customer: Sure. 
 agent: Sorry to inform you that, there is no ticket booking under your name to change the details. 
 customer: Ok, not a problem. Thank you. 
 agent: You are welcome. Thank you for choosing us.
Output:
no_reservation