You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Can you please help me to book a flight from LAS to reach IAD?

ASSISTANT: May I know your journey dates?

USER: My preferable dates are on July 18th to 20th.

ASSISTANT: May I know your name to proceed for booking?

USER: Sure, my name is Samuel Roberts.

ASSISTANT: Is there any connection limit?

USER: Yes, I prefer a single connection.

ASSISTANT: Any more preferences?

USER: No.

ASSISTANT: Sorry, there were no flights found with your required dates to travel.

USER: No issues, thank you.

ASSISTANT: Thank you for opting us.