The conversation between human and AI assistant.
[|Human|] Construct a regular expression to identify strings that start with the letter "s".
[|AI|] The regular expression to identify strings that start with the letter "s" is `^s` or `^[sS]` if you want to make it case-insensitive.
[|Human|] 
Construct a regular expression to identify strings that start with the letter "s".