#!/usr/bin/ruby 
# 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.

def fibonacci(n)
  return -1 if (n <= 0); 
  return 1 if (n <= 2);
  return fibonacci(n-1) + fibonacci(n-2)
end

if ARGV.length != 1 
   $stderr.printf "Usage:\n\t%s (n-th fibonacci # to calculate)\n", $0 
   exit -1
end

printf "fibonacci(%s): %d\n", ARGV[0], fibonacci(ARGV[0].to_i)