You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I am searching for a direct flight for my journey, can you please help me out with that?

ASSISTANT: I am glad that you have contacted us. I will help you.

USER: Thank you for accepting my request.

ASSISTANT: Please let me know your name.

USER: Sure, my name is Brian Young.

ASSISTANT: Thank you.

USER: It's alright.

ASSISTANT: Please help me with your planned travelling dates.

USER: Sure, my departure is on Dec 28 and please book my return ticket on Dec 30.

ASSISTANT: Please let me know with your depart and source airport codes.

USER: Sure, I want to travel from SFO to LAS.

ASSISTANT: Thank you. Please let me know with your preferred class to fly.

USER: I don't have any other preferences.

ASSISTANT: Please allow me a minute to check for the direct flight that matches your needs.

USER: Sure.

ASSISTANT: Brian Young, I am really sorry to inform you that there is no direct flight that reaches Las Vegas.

USER: Oh! Sad to hear that. Anyway, I will find another alternative to complete my trip. Thank you for checking.

ASSISTANT: Thank you for reaching us. Have a great time.

USER: Welcome.