input: Write a function to find the nth Fibonacci number. If n is less than 0, print "Incorrect input". If n is 0, return 0. If n is 1, return 1. For other values of n, recursively return the sum of the previous two Fibonacci numbers. The function should be named Fibonacci and take a single parameter n.
  
  assert Fibonacci(0)==0
  assert Fibonacci(1)==1
  assert Fibonacci(5)==5
  assert Fibonacci(10)==55
  assert Fibonacci(-3)=="Incorrect input"
output: def Fibonacci(n):
      if n < 0:
          return "Incorrect input"
      elif n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return Fibonacci(n-1) + Fibonacci(n-2)