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. Sarah Hall here. 
 agent: Hello, how can I help you today? 
 customer: Can you change my flight ticket reservation? 
 agent: Sure, we are here to help you. 
 customer: Ok. 
 agent: Ok, wait for some time. 
 customer: Sure. 
 agent: Thanks for waiting there is no reservation found on your name. 
 customer: Not a problem. Thank you. 
 agent: Thanks for approaching us.
Output:
no_reservation