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

Find a regex pattern that matches the following string:
1998%2508%2522T18%2E36%2E50.486 [/INST] pattern:
\d{4}%25\d{2}%25\d{2}T\d{2}%2E\d{2}%2E\d{2}\.\d{3} </s>