And is your question 'how do I do this in perl?' You don't say, but assume for a moment that it is.

If so, you'll find the answer to the first part of your problem by using Super Search or googling "site:Perlmonks.org max min column" (or something similar). Your question, if it's as stated in para 1, has been answered numerous times by Monks -- the most recent instance was, I think, just this week.

After that, solving the 'step value' requirement should be trivial if you have even the slightest inclination to learn Perl.

OTOH, if your question is how to do it better with shell commands, you might want to ask ShellMonks.