#include <stdio.h>
#include <stdlib.h>

typedef int element;
typedef struct ListNode{
	element data;
	struct ListNode* link;
}ListNode;

/*void error(char* message)
{
	fprintf(stderr,"%s\n",message);
	exit(1);
}
*/
ListNode* create_node(element data, ListNode* link)
{
	ListNode* new_node;
	new_node = (ListNode *)malloc(sizeof(ListNode));
	if(new_node == NULL){
		fprintf(stderr,"¸Þ¸ð¸®ÇÒ´ç¿¡·¯");
	exit(1);
	}
	new_node->data=data;
	new_node->link=link;
	return (new_node);
}

void insert_first(ListNode **phead , ListNode* node)
{
	if(*phead==NULL){
		*phead=node;
		node->link=node;
	}
	else
	{
		node->link=(*phead)->link;
		(*phead)->link=node;
	}
}
void insert_last(ListNode **phead , ListNode* node)
{
	if(*phead==NULL){
		*phead=node;
		node->link=node;
	}
	else
	{
		node->link = (*phead)->link;
		(*phead)->link = node;
		*phead = node;
	}
}
void display(ListNode *head)
{
	ListNode *p;
	if( head == NULL) return;

	p = head;
	do{
		printf("%d->",p->data);
		p = p->link;
		
	}while(p != head);
	printf("\n");
}
main()
{
	ListNode *list1=NULL;

	insert_first(&list1,create_node(10,NULL));
	insert_first(&list1,create_node(20,NULL));
	insert_last(&list1, create_node(30,NULL));
	display(list1);
}