Project Euler Problem 1

#! /usr/bin/ruby

def euler_1(n)
  numbers = []
  sum     = 0

  (0..n).each do
    n -= 1
    numbers << n if n % 3 == 0 or n % 5 == 0
  end

  numbers.each {|num| sum += num}

  puts "The sum is #{sum}"
end

n = ARGV[0].to_i
euler_1 n