You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Michelle Lewis.

ASSISTANT: How can I assist you today?

USER: I want to attend my friend marriage at PHL, can you please book me a ticket from IAD?

ASSISTANT: Sure, I can help you with that. May I know your planned travel dates please?

USER: I have planned to travel on May 20th and return on May 22nd.

ASSISTANT: May I know in which class do you prefer to travel?

USER: I am ok with any class.

ASSISTANT: May I know your airlines preference please?

USER: I don't have any airline preferences.

ASSISTANT: Do you have any specifications regarding departure and arrival time?

USER: I have planned to depart at morning time.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there are no flights available on those dates with your given details.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us, have a nice day.

USER: Thank you.