You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Benjamin Allen.

ASSISTANT: How can I aid you?

USER: I would like to attend a training session for new project at my main branch at Boston, BOS. Can you please help me in reservation with direct flight?

ASSISTANT: Sure. Kindly assign your preferred dates of travelling?

USER: My journey start on 09/24 and need to catch return flight on 09/26.

ASSISTANT: Please let me know your origin airport code?

USER: My source point is Oakland, OAK.

ASSISTANT: How much you can spend for airfare?

USER: I can spend 500.

ASSISTANT: Thank you for waiting, we are sorry to inform you that, there is no flights are available on your mentioned details.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for consulting us.