input: Write a function to find the nth Fibonacci number. If the input is less than 0, print "Incorrect input". For input 0, return 0. For input 1, return 1. For any other positive integer n, return the sum of the two preceding numbers in the Fibonacci sequence.
  
  def Fibonacci(n): 
      if n < 0: 
          print("Incorrect input") 
      elif n == 0: 
          return 0
      elif n == 1: 
          return 1
      else: 
          return Fibonacci(n-1) + Fibonacci(n-2)
  
  assert Fibonacci(5) == 5
  assert Fibonacci(10) == 55
  assert Fibonacci(0) == 0
  assert Fibonacci(1) == 1
  assert Fibonacci(7) == 13
output: def Fibonacci(n): 
      if n < 0: 
          print("Incorrect input") 
      elif n == 0: 
          return 0
      elif n == 1: 
          return 1
      else: 
          return Fibonacci(n-1) + Fibonacci(n-2)