short_mo = Set{4, 6, 9, 11}
cnt = 0

(1..12).each do |mm|
  (1..31).each do |dd|
    if mm == 2 && dd > 28
      next
    end
    
    if short_mo.includes?(mm) && dd == 31
      next
    end
    
    if mm == dd // 10 + dd % 10
      cnt += 1
    end
  end
end

puts cnt