#!/usr/bin/env python
# Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)
#
# This work is licensed under the Creative Commons Attribution-NonCommercial-
# ShareAlike License. To view a copy of this license, visit 
# http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
# Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
# 94105, USA.

import sys

def fibonacci(n):
   if n <= 0: return -1
   fib = 1; prev_fib = 1
   for i in xrange(2,n):
      (fib, prev_fib) = (fib+prev_fib, fib)
   return fib

if len(sys.argv) != 2:
   print >>sys.stderr, \
     "Usage:\n\t%s (n-th fibonacci # to calculate)\n" % (sys.argv[0])
   sys.exit(-1)

n = int(sys.argv[1])

print "fibonacci(%d): %d" % (n, fibonacci(n))