days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
count = 0
(0..11).each { |n|
  j = 0
  while j < days[n]
    sum = j / 10 + j % 10
    count += 1 if sum == n + 1
    j += 1
  end
}
puts count