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

Find a regex pattern that matches the following string:
2012$3B07$3B04T16:52:43.904 [/INST] pattern:
\d{4}\$3B\d{2}\$3B\d{2}T\d{2}:\d{2}:\d{2}\.\d{3} </s>