You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I want to visit San Francisco, please book my flight ticket from IAD to SFO.

ASSISTANT: Sure, please let me know your journey dates.

USER: I have to depart on July 15th and also please book my return ticket on July 17th.

ASSISTANT: Ok, do you have any class preference?

USER: No.

ASSISTANT: Ok, May I know your airline preference?

USER: I prefer for a normal-cost airlines.

ASSISTANT: Ok, Kindly mention your connection limit.

USER: I need single connection.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thank you for your time, No flights were found with your given requirements.

USER: Sad to hear that, thank you for checking.

ASSISTANT: Ok, May I know your name for documentation purpose?

USER: My name is Christopher Nelson.

ASSISTANT: Ok, Thank you for opting us.