number_of_day_in_month = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

count = 0
number_of_day_in_month.each_with_index do |item, index|
  month = index + 1
  item.times do |day_index|
    day = day_index + 1
    day_str = day.to_s
    sum_day = day_str.chars.map(&:to_i).sum
    if (month == sum_day)
      count += 1
    end
  end
end

p count