#include <stdio.h>
#include <stdlib.h>
 
// Structure for a doubly linked list node
struct Node {
    int data;
    struct Node *prev;
    struct Node *next;
};
 
// Function to create a doubly linked list
struct Node* createDoublyList(int n) {
    struct Node *head = NULL, *temp = NULL, *newNode = NULL;
    int data, i;
 
    if (n <= 0) {
        printf("Invalid number of nodes.\n");
        return NULL;
    }
 
    for (i = 1; i <= n; i++) {
        newNode = (struct Node*)malloc(sizeof(struct Node));
        if (newNode == NULL) {
            printf("Memory allocation failed!\n");
            exit(0);
        }
 
        printf("Enter data for node %d: ", i);
        scanf("%d", &data);
 
        newNode->data = data;
        newNode->prev = NULL;
        newNode->next = NULL;
 
        if (head == NULL) {
            head = newNode;
        } else {
            temp->next = newNode;
            newNode->prev = temp;
        }
 
        temp = newNode;
    }
 
    return head;
}
 
// Function to display the list forward
void displayForward(struct Node *head) {
    struct Node *temp = head;
    printf("\nDoubly Linked List (Forward): ");
    while (temp != NULL) {
        printf("%d <-> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}
 
// Function to display the list in reverse order
void displayBackward(struct Node *head) {
    struct Node *temp = head;
    if (head == NULL) {
        printf("\nList is empty.\n");
        return;
    }
 
    // Move to last node
    while (temp->next != NULL) {
        temp = temp->next;
    }
 
    printf("\nDoubly Linked List (Backward): ");
    while (temp != NULL) {
        printf("%d <-> ", temp->data);
        temp = temp->prev;
    }
    printf("NULL\n");
}
 
int main() {
    struct Node *head = NULL;
    int n;
 
    printf("Enter number of nodes: ");
    scanf("%d", &n);
 
    head = createDoublyList(n);
 
    displayForward(head);
    displayBackward(head);
 
    return 0;
}