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, how may I abet you today? 
 customer: I am Eric Evans. I need to go for a emergency surgery in Denver, DEN. Could you help me in booking me a direct light? 
 agent: Sure, can I know your travelling dates? 
 customer: 06/15 - 06/17 are my travelling dates. 
 agent: May I know your source point? 
 customer: My source airport is Chicago, ORD. 
 agent: We found a flight of jetblue airline, flight number as 1015 with the fare of 200. Shall I book it? 
 customer: I need a direct flight. 
 agent: Ok, we could not find any direct flight. 
 customer: Ok. Thank you. 
 agent: Than you for availing us.
Output:
no_flight