ans = 0
[0,
 31, # 1
 28,
 31,
 30, # 4
 31,
 30,
 31, # 7
 31,
 30,
 31, # 10
 30,
 31
].each_with_index do |d, i|
  1.upto(d) do |n|
    if i == n % 10 + n / 10
      ans += 1
    end
  end
end

puts ans