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

struct node {
int num;
struct node *next;
struct node *prev;
};

struct node *first = NULL;
struct node *last = NULL;
struct node *temp = NULL;
	
int main()
{
	int ch=0;
	int tmp;
	while(ch != 4)
	{
		printf("Enter 1 to add a node\nEnter 2 to display the list in forward order \nEnter 3 to display the list in reverse order \nEnter 4 to exit \nEnter choice: ");
		scanf("%d",&ch);

		if(ch == 1)
		{
			if(first == NULL)
			{
				first = (struct node *)malloc(sizeof(struct node));
				printf("Enter a number: ");
				scanf("%d",&tmp);
				first->num = tmp;
				first->next = NULL;
				first->prev = NULL;
				last = first;
				printf("Node created\n");
			}
			else
			{
				temp = malloc(sizeof(struct node));
				printf("Enter a number: ");
				scanf("%d",&tmp);
				temp->num = tmp;

				last->next = temp;
				temp->prev = last;

				last = last->next;
				printf("Node created\n");
			}
		}
		else if(ch == 2)
		{
			if(first == NULL)
			{
				printf("List is empty\n");
			}
			else
			{
				temp = first;
				while(temp != NULL)
				{	
					printf("%d ",temp->num);
					temp = temp -> next;
				}
				printf("\n");
			}
		}
		else if(ch == 3)
		{
			if(first == NULL)
			{
				printf("List is empty\n");
			}
			else
			{
				temp = last;
				while(temp != NULL)
				{	
					printf("%d ",temp->num);
					temp = temp -> prev;
				}
				printf("\n");
			}
		}
		else if(ch == 4)
		{
//			exit(0);
		}
	}
}