Definition: 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: Hi. I am Mary Allen. 
 agent: Hello, how may I help you at this moment? 
 customer: I need to amend my reservation, can you help me out? 
 agent: Sure, I will help you. Please wait for a while. 
 customer: Sure, take your own time. I will wait for your response. 
 agent: Sorry, there is no reservation existing on your name. 
 customer: That's ok, no problem. Thank you for your information. 
 agent: You are welcome. Thank you for reaching us, have a nice day.
Output:
no_reservation