class Solution:
def oddEvenList(self, head: ListNode) -> ListNode:
first = ListNode(None)
f_i = first
second = ListNode(None)
s_i = second
index = head
count = 0
while index:
if count % 2 == 0:
f_i.next = index
f_i = index
elif count % 2 == 1:
s_i.next = index
s_i = index
index = index.next
count += 1
f_i.next = second.next
s_i.next = None
return first.next