while (my $line = <$INPUT>) {
#chomp; # this gives me syntax errors???
...
}

The  chomp; statements in the code in this post operate on the default  $_ scalar, which does not seem to be initialized anywhere in the code. Let me suggest that what you are seeing is not a syntax error but a "Use of uninitialized value ..." warning (not an error) because you have very wisely enabled warnings in your code.

c:\@Work\Perl\monks>perl -wMstrict -le
"chomp;
"
Use of uninitialized value $_ in scalar chomp at -e line 1.
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A solution is to chomp something that has been assigned a value, like  $line in the while-loop conditional expression:
    chomp $line;