You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to travel from DFW to SFO. Can you help me to book a flight ticket?

ASSISTANT: Sure, can I know your travelling dates please?

USER: I want to fly in the flight on May 17 and May 19.

ASSISTANT: Is there any airline preference for you?

USER: I prefer normal-cost airline.

ASSISTANT: Do you need any other requirements?

USER: I want to depart in morning time.

ASSISTANT: May I know your good name please?

USER: Kevin Carter.

ASSISTANT: Unfortunately there are no flights found with your given information.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for choosing us.