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. 
 agent: Hello, good morning. 
 customer: I am Timothy Martin. 
 agent: How can I help you? 
 customer: I booked a ticket last week, but I heard that my visiting place is attacked by sand cyclone. Will you please cancel my recent reservation? 
 agent: Sure, please wait a while. 
 customer: Ok. 
 agent: There is no reservation on your name, Martin. Do you want to know anything else? 
 customer: Ok, no problem. No, thank you for your service. 
 agent: You are welcome.
Output:
no_reservation