Linked List

def solve():
    class Node:
        def __init__(____):
            self.val = val
            self.next = None
    
    head = Node(____)
    head.next = Node(____)
    head.next.next = Node(____)
    
    new_node = Node(____)
    new_node.next = head
    head = new_node
    
    result = []
    current = head
    while current:
        result.append(str(____))
        current = current.next
    
    print('____'.join(____))