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. 
 agent: Hello, how may I oblige you today? 
 customer: I am Helen Williams. I want to visit  Navajo Adventure at Las Vegas, LAS to enjoy myself, can you please help me to book a ticket from Austin, AUS? 
 agent: Sure, we are glad to help you. 
 customer: Thank you. 
 agent: When are you going to travel? 
 customer: I have planned to travel on 07/05 and 07/07. 
 agent: Ok, do you need a economy class? 
 customer: I am comfortable with any class. 
 agent: Could you please wait a minute? 
 customer: Ok, I will wait. 
 agent: Thanks for waiting, currently there are no flights running to your destination due to bad weather condition. 
 customer: Ok, no problem, I will choose other way to rich my destination. Thank you. 
 agent: Thank you for choosing us. Have a good day.
Output:
no_flight