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.$y){
	/./;
	print$&;
	s///for$x||=$a{$&},$y||=$b{$&};
}