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: Hello, I am Paul Gonzalez. 
 agent: Hello, in what way I can be at your service? 
 customer: I want to meet my old collage friends at Boston, can you please book me a ticket? 
 agent: Sure, can I have your airport codes? 
 customer: My airport codes are from IAH to BOS. 
 agent: Ok, when are you planning to travel? 
 customer: I would like to leave between 07/14 and 07/16. 
 agent: Do you have any other preferences? 
 customer: I need a connecting flight. 
 agent: Sorry to inform you Paul Gonzalez, no airline is providing service on your route. 
 customer: Ok, no problem. Thank you. 
 agent: Thank you for choosing our service.
Output:
no_flight