You will be given a definition of a task first, then some input of the task.
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

customer: Hi. 
 agent: Hello. 
 customer: I am Sandra Mitchell. 
 agent: How can I assist you today? 
 customer: Can you help me in booking from HOU to PHL, as there is a business meeting? 
 agent: Sure, I can help you with that. May I know your planned travel dates please? 
 customer: My trip dates are 02/16 to 02/18. 
 agent: Ok, may I know your class preference? 
 customer: No, but my depart time should be in afternoon. 
 agent: Ok, do you have any other specifications? 
 customer: I need a connecting flight. 
 agent: Ok, please wait a while. 
 customer: Sure. 
 agent: Sorry to inform you that there are no flights available for you on those dates. 
 customer: No issue, thank you. 
 agent: Thank you for choosing us.
Output:
no_flight