#include<iostream>
using namespace std;
typedef struct list
{
	int data;
	list* prior;
	list* next;
}list,*linklist;
void Createlist(linklist& l,int n)//创建（不带头节点）双向链表
{
	l = new list;
	l->prior = NULL;
	l->next = NULL;
	linklist p,q;
	cin >> l->data;
	q = l;
	for (int i = 1; i < n; i++)
	{
		p = new list;
		cin >> p->data;
		q->next = p;
		p->prior = q;
		q = p;
	}
	q->next = l;
	l->prior = q;
}
void Insertlist(linklist& l, int n, int e)//在第i个位置插入e
{
	linklist p,s;
	s = new list;
	s->data = e;
	p = l;
	for (int i = 1; i < n; i++)
	{
		p = p->next;
	}
	s->prior = p->prior;
	p->prior->next = s;
	s->next = p;
	p->prior = s;
}
void Deletelist(linklist& l, int n)//删除第i个元素
{
	linklist p,q;
	p = l;
	for (int i = 1; i < n; i++)
	{
		p = p->next;
	}
	p->prior->next = p->next;
	p->next->prior = p->prior;
}
void Printlist(linklist& l,int &n)//输出两遍链表
{
	cout << "循环输出两遍链表" << endl;
	linklist p;
	p = l;
	for (int i = 1; i <= 2*n; i++)
	{
		cout << p->data << " ";
		p = p->next;
	}
	cout << endl;
}
int main()
{
	linklist l;
	cout << "链表长度：" << endl;
	int n;
	cin >> n;
	Createlist(l,n);
	Printlist(l,n);
	cout << "在第i个元素插入e(分别输入i，e)：" << endl;
	int i, e;
	cin >> i >> e;
	Insertlist(l, i, e);
	n++;
	Printlist(l,n);
	cout << "删除第i个元素：" << endl;
	cin >> i;
	Deletelist(l, i);
	n--;
	Printlist(l,n);
}