@union = @intersection = @left = @right = ();
        %count = ();
        my %left; @left{ @array1 } = 1 x @array;
        my %common;
        foreach $element (@array2) {
            if (exists $left{ $element }) {
                $common{ $element } = delete $left{ $element };
            } else {
                $right{ $element } = 1;
            };
        };

        print "Keys only on the left side:\n";
        for (keys %left) {
            print "$_\n";
        };

        print "Keys only on the right side:\n";
        for (keys %right) {
            print "$_\n";
        };

        print "Keys found on both sides:\n";
        for (keys %common) {
            print "$_\n";
        };