#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 a given position
struct Node* insertAtPosition(struct Node *head, int data, int pos) {
    struct Node *newNode = createNode(data);
    struct Node *temp = head;
    int i;
 
    if (pos <= 1) {  // Insert at beginning
        newNode->next = head;
        if (head != NULL)
            head->prev = newNode;
        head = newNode;
        return head;
    }
 
    // Traverse to the position
    for (i = 1; i < pos - 1 && temp != NULL; i++)
        temp = temp->next;
 
    if (temp == NULL) {
        printf("Position out of range! Inserting at end.\n");
        return head;
    }
 
    newNode->next = temp->next;
    newNode->prev = temp;
 
    if (temp->next != NULL)
        temp->next->prev = newNode;
 
    temp->next = newNode;
 
    return head;
}
 
// Function to display the list
void displayList(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, pos, i;
 
    printf("Enter number of initial nodes: ");
    scanf("%d", &n);
 
    // Creating initial list
    for (i = 1; i <= n; i++) {
        printf("Enter data for node %d: ", i);
        scanf("%d", &data);
        head = insertAtPosition(head, data, i); // Insert at end initially
    }
 
    displayList(head);
 
    // Insert at user-defined position
    printf("\nEnter data to insert: ");
    scanf("%d", &data);
    printf("Enter position to insert: ");
    scanf("%d", &pos);
 
    head = insertAtPosition(head, data, pos);
 
    displayList(head);
    return 0;
}