To select only words you can use \W+ (see perlre non-words):

    ...
    my @words = split /\W+/;
    ...
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For show only first 5 occurs you can use this syntax:

foreach $w ( 
    (
      sort { $count{$b} <=> $count{$a} } keys %count
    ) [0..4] ) {
...
}
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