I have to Convert a number into linked list such that each digit is in a node and pointing to node having next digit.The function should return head of the linked list. e.g input 120 should create a list of Nodes 1 -> 2 -> 0 and return the reference.If it is a negative number say -120 it should return -1->-2->0.I tried to do it in this way:

```
def number_to_list(number):
    head,tail = None,None
    for x in str(number):
        if x<0:
           x = -int(x)
           node = Node(int(x))
        else:
           node = Node(int(x))
        if head:
           tail.next = node
        else:
            head = node
        tail = node
    return head
    pass

```

It is working fine for positive numbers but if I pass -120.It is showing an error:

```
ValueError: invalid literal for int() with base 10: '-'. 

```

How can I fix it.