You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you help me to book a economy class flight ticket?

ASSISTANT: Let me know your travelling dates.

USER: My preferable journey dates are Dec 22 and Dec 24.

ASSISTANT: Can I know your airport codes?

USER: My airport codes are IAD and LAS.

ASSISTANT: Do you have any preference?

USER: I would like to depart in the morning time.

ASSISTANT: Let me know your name.

USER: My name is Scott Collins.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.