def sum67(nums):
  on = 0
  count = 0
  for i in range(len(nums)):

   if nums[i] == 6 and on == 0:
    nums[i] = 0
    on = True

   if nums[i] == 7 and on == 1:
    nums[i] = 0
    on = 0

   if on == 1:
    nums[i] = 0

  for i in range(len(nums)):
   count = count + nums[i]

  return count