@union = @intersection = @difference = ();
	%count = ();
        foreach $element (@a, @b) { $count{$element}++ }
        foreach $element (keys %count) {
		push @union, $element;
		push @{ $count{$element} > 1 ? \@intersection : \@difference }, $element;
    	}

	foreach $int (@difference){
		if ($int ne " "){
			@fname = split(/ /, $int);
			print "\n difference elements --> $fname[0]\n";
		}
	}