class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

def reverse(pHead):
    node = ListNode(None)
    node.next = pHead
    tmp = pHead
    while(tmp.next!=None):
        tmp2 = tmp.next
        tmp.next = tmp2.next
        tmp2.next = node.next
        node.next = tmp2
    return node.next


#
class Solution:
    def FindFirstCommonNode(self , pHead1 , pHead2 ):
        if (pHead1==None)or(pHead2==None): return 0;
        p1 = reverse(pHead1)
        p2 = reverse(pHead2)
        while(p1.next==p2.next)and(p1.next!=None):
            p1 = p1.next
            p2 = p2.next
        return p1