You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Donna Martinez.

ASSISTANT: How may I help you?

USER: I would like to meet my college friends after a long gap, please help me in booking a ticket.

ASSISTANT: Ok, please provide your airport codes.

USER: My airport codes are from OAK to LAS.

ASSISTANT: Please provide me your journey dates.

USER: My journey dates are from 05/10 to 05/12.

ASSISTANT: Please give me a minute.

USER: Sure.

ASSISTANT: Donna, there are no flights available at this moment.

USER: Ok, no problem. I will go by another means of transport. Thank you for your time.

ASSISTANT: Thank you for choosing us.