typedef int ElemenType
int Length(List PtrL)//求长度 
{
	List p = PtrL;
	int j = 0;
	while(p)
	{
		p=p->Next;//指针往后挪
		j++; 
	}
	return j;
}
List FindKth(int K,List PtrL)//按序号查找 
{
	List p = PtrL;
	int i = 1;
	while(p!=NULL&&i<K)
	{
		p = p->Next;
		i++;
	}
	if(i==K)
		return p;
	else
		return NULL;
}
List Find(ElemenType X,List PtrL)//按值查找 
{
	List p = PtrL;
	while(p!=NULL&&p->Data!=X)
		p=p->Next;
	return p;	
}
int InSert(ElemenType)