# fibfun.py
# Neal Nelson
#
# Fibonacci calculation using a for loop from Chapter 3 (Ch3p16).
#   Note the handy use of simultaneous assignment from Chapter 2 p36.
#
# This version uses a separate function (Chapter 6) to compute the fib (Ch6p7).
# 


def fib(n):
  fibold = 1
  fibnew = 1
  for i in range(2,n):
    fibnew, fibold = fibold + fibnew, fibnew

  return fibnew

def main():
  n = input("Fibonacci calculator - enter a positive number: ")
  print "That Fibonacci number is: ", fib(n)

main()