class _Node:

__slots__ = '_element', '_next'

def __init__(self, element, next):

self._element = element

self._next = next

class CircularLinkedList:

def __init__(self):

self._head = None

self._tail = None

self._size = 0

def __len__(self):

return self._size

def isempty(self):

return self._size == 0

def addlast(self, e):

newest = _Node(e, None)

if self.isempty():

newest._next = newest

self._head = newest

else:

newest._next = self._tail._next

self._tail._next = newest

self._tail = newest

self._size += 1

def addfirst(self,e):

newest = _Node(e, None)

if self.isempty():

newest._next = newest

self._head = newest

self._tail = newest

else:

self._tail._next = newest

newest._next = self._head

self._head = newest

self._size += 1

def display(self):

p = self._head

i = 0

while i < len(self):

print(p._element,end='-->')

p = p._next

i += 1

print()

def search(self,key):

p = self._head

index = 0

while index < len(self):

if p._element == key:

return index

p = p._next

index = index + 1

return -1

C = CircularLinkedList()

C.addlast(7)

C.addlast(4)

C.addlast(12)

C.addlast(8)

C.addlast(3)

C.display()

print('Size:',len(C))

C.addfirst(25)

C.display()

print('Size:',len(C))