For whatever reason, the line:

 
open(IN, "<".shift) or die;
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doesn't work for me in ActiveState Perl 5.6 /NT workstation when I call the above program as

perl tempo.pl ip.dat djb.dat
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However, the program works great when I replace that line with:

open(IN, "<ip.dat") or die;
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and call it as:

perl tempo.pl djb.dat
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