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 can I help you today? 
 customer: Can you please make me a plane reservation in a flight that returns in the morning time? 
 agent: Sure, when you are planning to travel? 
 customer: I will start on Apr 22nd and return on Apr 24th. 
 agent: Can you please forward your airport codes? 
 customer: My origin is ORD and destination is PHX. 
 agent: Do you have any connection limit? 
 customer: Yes, I need 1 stop over. 
 agent: May I know your name please? 
 customer: I am Mary Harris. 
 agent: Unfortunately there is no flight found with your given information. 
 customer: That's alright, thanks for your assistance. 
 agent: Thank you for opting us.
Output:
no_flight