require "date"

module M
  refine Integer do
    def sum
      to_s.chars.map(&:to_i).sum
    end
  end

  refine Date do
    def happy_day?
      month == day.sum
    end
  end
end
using M

puts (Date.new(2015, 1, 1)..Date.new(2015, 12, 31)).select(&:happy_day?).count