use strict;
use warnings;

my @userWords = qw(kicking kick);
my %words = map {chomp; lc $_ => 0} split ' ', <DATA>;

exists $words{lc $_} && $words{$_} >= 0 ? ++$words{$_} : --$words{$_}
    for @userWords;

for (sort keys %words) {
    next if ! $words{$_};
    print "not " if $words{$_} < 0;
    print "found $_\n";
}

__DATA__
George Best is Alive and Kicking