#!perl
use strict;
use warnings;
use autodie;

my $pre       = $ARGV[0];
my $max_lines = 300_000;
my $linenum   = 0;
my $filenum   = 0;

open my $fileout, '>', $pre . '-' . $filenum;

while (my $line = <>)
{
    $line =~ s/ \s* $ //x;      # remove trailing whitespace (incl. "\r\n")

    if ($line ne '')            # ignore blank lines
    {
        if ($linenum++ < $max_lines)
        {
            print $fileout $line, "\n";
        }
        else
        {
            close $fileout;
            open  $fileout, '>', $pre . '-' . ++$filenum;
            print $fileout $line, "\n";
            $linenum = 1;
        }
    }
}

close $fileout;