struct ListNode {
	int m_nKey;
	ListNode m_pNext;
};
ListNode* merge(ListNode* pHead1, ListNode* pHead2) {
	if (pHead1 == NULL) {
		return pHead2;
	}
	if(pHead2 == NULL) {
		return pHead1;
	}

	ListNode* mergedList = NULL;
	if (pHead1->m_nKey < pHead2->m_nKey) {
		mergedList = pHead1;
		mergedList->m_pNext = merge(pHead1->m_pNext, pHead2);
	}
	else {
		mergedList = pHead2;
		mergedList->m_pNext = merge(pHead2->m_pNext, pHead1);
	}

	return mergedList;
}