class Solve
  def initialize
    _ = gets.to_i
    @a_list = gets.chomp.split.map(&:to_i)
  end

  def run
    len = @a_list.size
    (len - 1).downto(3) do |i|
      if @a_list[i] != 0
        @a_list[i-2] += @a_list[i]
        @a_list[i] = 0
      end
    end

    3.downto(0) do |i|
      if @a_list[i]
        puts i
        puts @a_list[0..i].join(' ')
        break
      end
    end
  end
end

 Solve.new.run