Detailed 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
Problem:customer: Hi. 
 agent: Hello, what kind of help do you want? 
 customer: I want change an existing reservation due to sudden change in my trip. 
 agent: Sure, may I know your name? 
 customer: Can you help me with that? I am Richard White. 
 agent: Sure, we are here to assist you. Ok, please wait for a moment. 
 customer: Ok. 
 agent: Sorry to say, we did not find any reservation to change on your name. 
 customer: Ok ,  Thank you for your response. 
 agent: Thanks for picking our service.
Solution:
no_reservation