You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Mark Clark.

ASSISTANT: How may I assist you?

USER: I want to travel from IAH to SFO.

ASSISTANT: Ok Mark, please tell me your travelling dates?

USER: My preferable dates are from 10/01 to 10/03.

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

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you for reaching us.