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 help you? 
 customer: I am Paul Scott, want to travel from DCA to AUS. Please help me in booking my ticket. 
 agent: Sure, on which dates you are planning to travel? 
 customer: Sure, my trip dates are from 01/18 to 01/20. Please check the flight with 0 connection. 
 agent: Sorry, there is no flights available. 
 customer: It's ok, thank you. 
 agent: Most welcome.
Output:
no_flight