import java.util.*;
class LinkedList {
static Node head1, head2;
static class Node {
int data;
Node next;
Node(int d)
{
data = d;
next = null;
}
}
/*function to get the intersection point of two linked
lists head1 and head2 */
int getNode()
{
int c1 = getCount(head1);
int c2 = getCount(head2);
int d;
if (c1 > c2) {
d = c1 - c2;
return _getIntesectionNode(d, head1, head2);
}
else {
d = c2 - c1;
return _getIntesectionNode(d, head2, head1);
}
}
/* function to get the intersection point of two linked
lists head1 and head2 where head1 has d more nodes than
head2 */
int _getIntesectionNode(int d, Node node1, Node node2)
{
int i;
Node current1 = node1;
Node current2 = node2;
for (i = 0; i < d; i++) {
if (current1 == null) {
return -1;
}
current1 = current1.next;
}
while (current1 != null && current2 != null) {
if (current1.data == current2.data) {
return current1.data;
}
current1 = current1.next;
current2 = current2.next;
}
return -1;
}
/*Takes head pointer of the linked list and
returns the count of nodes in the list */
int getCount(Node node)
{
Node current = node;
int count = 0;
while (current != null) {
count++;
current = current.next;
}
return count;
}
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int n1 = sc.nextInt();
LinkedList list = new LinkedList();
list.head1.data = sc.nextInt();
for(int i = 1;i<n1;i++){
list.head1.next.data = sc.nextInt();
}
int n2 = sc.nextInt();
list.head2.data = sc.nextInt();
for(int i = 1;i<n2;i++){
list.head2.next.data = sc.nextInt();
}
System.out.println(list.getNode());
}
}