You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Joshua Thomas. I am planning to visit Houston Zoo which is in IAH.

ASSISTANT: Nice meeting you Thomas.

USER: Can you help me in booking a ticket from IAD?

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

USER: My travel dates are from 10/19 to 10/21.

ASSISTANT: Sorry to inform you, there is no flight available which is travelling to your destination on your provided dates.

USER: It's fine. Anyway, thank you for your help.

ASSISTANT: It's my pleasure. Have a nice day.

USER: Thank you.