input: def Fibonacci(n: int) -> int:
      """ A simple recursive function to find the nth Fibonacci number.
      >>> Fibonacci(5)
      5
      >>> Fibonacci(10)
      55
      >>> Fibonacci(0)
      0
      >>> Fibonacci(-1)
      "Incorrect input"
      """
      if n < 0:
          return "Incorrect input"
      elif n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return Fibonacci(n-1) + Fibonacci(n-2)
output:     if n < 0:
          return "Incorrect input"
      elif n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return Fibonacci(n-1) + Fibonacci(n-2)