You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Ryan Evans.

ASSISTANT: How can I help you?

USER: Can you please book a flight ticket from IAD to DEN?

ASSISTANT: Yes, can you share me your travelling dates?

USER: Sure, I need to travel on dates of 06/18 and 06/20.

ASSISTANT: Give me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry to inform you that there are no flights found on your requested dates.

USER: Oh! It is sad to hear. Anyway, I will choose another agency this time.

ASSISTANT: Thank you for consulting us.

USER: Thank you for your time.