<s>[INST] <<SYS>>
You are an expert in regular expressions (regex)
<</SYS>>

Find a regex pattern that matches the following string:
1999$5F12$5F21T00:27:31Z [/INST] pattern:
\d{4}\$5F\d{2}\$5F\d{2}T\d{2}:\d{2}:\d{2}Z </s>