Instructions: 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, Stephen Perez here. 
 agent: Hello Stephen, how can I assist you? 
 customer: I want to book a ticket from AUS to HOU on the dates 06/13 to 06/15. Could you please help me out? 
 agent: Ok stephen, please hold on for a moment. 
 customer: Ok. 
 agent: Sorry for the inconvenience stephen, we could not find a flight with your matching requirements. 
 customer: Ok, that's fine. Thank you for your response. 
 agent: You are welcome. Have a nice day.
Output:
no_flight