one for the weekend

I got a .TXT with three lines:
unknown
unknown
pcm_s16le
and want to read out line 1, 2 and 3 separately for populating variables. For example line 3, I tried
(?im)(?:\r\n?|\n){2}(\w+) and
(?:\r\n?|\n){2}(\w+) and
\n\n(\w+) and so on...
but it returns "unknown" instead of "pcm_s16le". I tried several regex-tester (https://www.regexpal.com/ and https://regexr.com/ for example) and cruised through several forums for getting this running - but no success.
Any idea?
thanks in advance,
tom