You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Melissa Lee.

ASSISTANT: How may I assist you?

USER: I just want to visit my family in San Francisco, could you help me in booking the ticket?

ASSISTANT: Sure, may I know your travel details please?

USER: I want to travel from IAD to SFO.

ASSISTANT: Can you please tell me your travel dates?

USER: It's from 06/05 to 06/07.

ASSISTANT: Ok. Please wait for a moment.

USER: Ok.

ASSISTANT: Let me check the availability.

USER: Ok.

ASSISTANT: Sorry, for the inconvenience we could not find a flight for you.

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

ASSISTANT: Welcome.