// Doubly Linked list class
class DoublyLinkedList
{
    // head of list
    Node head;
 
    // Node class
    class Node
    {
        int val;
        Node next, pre;
          
        // Constructor to create a new node
        Node(int v) {
           val = v;
        }
    }
}

# Node class
class Node:
    # Function to initialize the node object
    def __init__(self, v):
        self.val = v  # Assign value
        self.next = None  # Initialize next as null
  
# Doubly Linked List class
class DoublyLinkedList:
    # Function to initialize the Linked List
    def __init__(self): 
        self.head = None