k difference

$s = <STDIN>;
my ($N, $K, @arr);
($N, $K) = split /\s/, $s;
$s = <STDIN>;
@arr = split /\s/, $s;
my %hash;
my $cnt = 0;
my %intersectlist;
foreach my $k(@arr) {
        $intersectlist{$k + $K} = 1;
}
for my $k(@arr) {
        $cnt++ if exists $intersectlist{$k};
}
print $cnt;