You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, thanks for connecting with us. How can I help you?

USER: My name is Charles Mitchell.

ASSISTANT: I hope your doing good Charles?

USER:  I want to attend my friend's marriage at San Fransisco , could you please help me with booking a flight ticket?

ASSISTANT: Sure, please tell your exact journey details?

USER: Source airport code is DCA and destination airport code is SFO.

ASSISTANT: Ok, your travelling dates please?

USER: The travel dates are from 01/31 to 02/02.

ASSISTANT: Sorry, there are no flights with your requested dates.

USER: That's fine.

ASSISTANT: Ok.

USER: Thank you for your help.

ASSISTANT: Thank you and have a nice day.