#include <stdio.h>
#include <stdlib.h>
 
// Structure definition
struct Node {
    int data;
    struct Node *prev;
    struct Node *next;
};
 
// Function to create a new node
struct Node* createNode(int data) {
    struct Node *newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->prev = NULL;
    newNode->next = NULL;
    return newNode;
}
 
// Function to insert a node at the end
struct Node* insertAtEnd(struct Node *head, int data) {
    struct Node *newNode = createNode(data);
    struct Node *temp = head;
 
    if (head == NULL) {
        head = newNode;
        return head;
    }
 
    // Traverse to the last node
    while (temp->next != NULL)
        temp = temp->next;
 
    // Link new node
    temp->next = newNode;
    newNode->prev = temp;
 
    return head;
}
 
// Function to display the list forward
void displayForward(struct Node *head) {
    struct Node *temp = head;
    printf("\nDoubly Linked List: ");
    while (temp != NULL) {
        printf("%d <-> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}
 
int main() {
    struct Node *head = NULL;
    int n, data, i;
 
    printf("Enter number of nodes to insert at end: ");
    scanf("%d", &n);
 
    for (i = 1; i <= n; i++) {
        printf("Enter data for node %d: ", i);
        scanf("%d", &data);
        head = insertAtEnd(head, data);
    }
 
    displayForward(head);
    return 0;
}