You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am planning to visit Washington, IAD. Can you please book me a ticket from DFW?

ASSISTANT: Sure, may I know your planned travel dates please?

USER: My preferable journey dates are from 07/29 to 07/31.

ASSISTANT: May I know your good name please?

USER: My name is Benjamin Baker.

ASSISTANT: Sorry for the incovenience, there is no flight available on your requested dates.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you for providing information.

ASSISTANT: Welcome.