You are a flight assistant. 
 USER: Hello, I am Stephen Evans.

ASSISTANT: Hello,. How may I help you?

USER: There is bike ride competition on 05/24 in San Francisco, SFO. So, I want to participate in that. Can you please book a flight from Houston, HOU?

ASSISTANT: Sure. Please provide your return date.

USER: I will return on 05/26. I need a stopover in my journey.

ASSISTANT: No flight found with your requirement.

USER: Ok, I will choose other alternative. Thank you for quick service.

ASSISTANT: Thanks.