input: 
  
  def fibfib(n: int):
      """The FibFib number sequence is a sequence similar to the Fibbonacci sequnece that's defined as follows:
      fibfib(0) == 0
      fibfib(1) == 0
      fibfib(2) == 1
      fibfib(n) == fibfib(n-1) + fibfib(n-2) + fibfib(n-3).
      Please write a function to efficiently compute the n-th element of the fibfib number sequence.
      >>> fibfib(1)
      0
      >>> fibfib(5)
      4
      >>> fibfib(8)
      24
      """
  
output:     if n == 0 or n == 1:
          return 0
      elif n == 2:
          return 1
      
      a, b, c = 0, 0, 1
      for _ in range(3, n + 1):
          a, b, c = b, c, a + b + c
      
      return c