/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
public:
    ListNode* FindFirstCommonNode( ListNode* pHead1, ListNode* pHead2) {
        ListNode* p1=pHead1;
        ListNode* p2=pHead2;
        while(p1!=p2)
        {
            p1=(p1==NULL?pHead2:p1->next);
            p2=(p2==NULL?pHead1:p2->next);
        }
        return p1;
    }
};