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
Q: customer: Hi. 
 agent: Hello. How can I assist you? 
 customer: I am Edward Nelson. I want to change my existing reservation? Can you help me out? 
 agent: Sure, Edward. Please wait a minute. 
 customer: Sure. 
 agent: Edward, there is no reservation available with your details. 
 customer: Oh! that's fine. 
 agent: Thank you for contacting us. 
 customer: Thank you for your search.
A:
no_reservation