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: Hello. 
 agent: Hello, how may I help you? 
 customer: Mary Martin here. Actually I made a earlier reservation to go for a trip with my friends, but heavy work load in office I want to change my reservation. 
 agent: Sure, please wait for a while. 
 customer: Sure. 
 agent: Sorry Mary, there is no active reservation found with your name in our records. 
 customer: That's ok, no problem. 
 agent: Most welcome. 
 customer: Thank you.
A:
no_reservation