You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me to book a flight ticket from SFO to LAS?

ASSISTANT: Sure, can you please mention your departure and arrival dates of your journey?

USER: My travelling dates are May 7 to May 9.

ASSISTANT: I need your preferred connection limit to check for a flight.

USER: I need a single connection of flight.

ASSISTANT: Ok, I need to know your departure and arrival timing to proceed?

USER: No.

ASSISTANT: Any other specifications do you have?

USER: I prefer to fly in big brand airlines.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: May I know your name please?

USER: Margaret Walker.

ASSISTANT: Thank you for waiting Margaret Walker, sorry to inform you that unfortunately there is no flights available by the given details.

USER: No problem, thanks for your information.

ASSISTANT: Thanks for reaching us.