def how_many_days(month)
  case month
  when 2
    28
  when 4, 6, 9, 11
    30
  else
    31
  end
end

def how_many_happy_days
  count = 0
  (1..12).each do |month|
    (1..how_many_days(month)).each do |day|
      count += 1 if month == day.to_s.split(//).map(&:to_i).inject(:+)
    end
  end
  count
end

puts how_many_happy_days