for$v(a,b){
	for(1..<>){
		$_=<>;
		chop;
		/./;
		$$v{$&}=$_;
	}
}
@c=grep$a{$_},keys%b;
exit!print-1if$#c;
$x=$a{"@c"};
$y=$b{"@c"};
while($x.$y){
	$y=~/./,$x=$a{$&}if!$x;
	$x=~/./,$y=$b{$&}if!$y;
	$x=~s/.//;
	$y=~s/.//;
	print$&;
}