#!/usr/local/bin/ruby
# -*- mode: ruby -*-
# $Id: fibo.ruby,v 1.2 2000/12/24 19:10:50 doug Exp $
# http://www.bagley.org/~doug/shootout/

def fib(n)
    if n < 2 then
    1
    else
    fib(n-2) + fib(n-1)
    end
end

N = Integer(ARGV.shift || 1)
puts fib(N)