Given the task definition and input, reply with output. 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

customer: Hello. 
 agent: Hello, how may I help you? 
 customer: Can you please help me to change my active reservation as my meeting was changed? 
 agent: Sure, may I know your name please? 
 customer: Gregory Johnson. 
 agent: Ok, please wait for a while. 
 customer: Ok. 
 agent: Sorry, there is no active reservation found with your name in our records. 
 customer: Ok, no problem in that. Thank you. 
 agent: Most welcome.
no_reservation