from util.io import readvalue


def fibonacci(n):
	if(n in (0,1)):
		return 1
	return fibonacci(n - 1) + fibonacci(n - 2)

if( __name__ == "__main__"):
	
	def nonnegative_int(s):
		i = int(s)
		if(i < 0):
			raise ValueError("{} is smaller than zero".format(i))
		return i

	n = readvalue("n > ", nonnegative_int)
	print("fibonacci(", n, ") = ", fibonacci(n))