local function is_safe(a)
  local up = false
  local down = false
  local prev = nil

  for i, number in ipairs(a) do
    number = tonumber(number)

    if prev == nil then
      prev = number
      goto continue
    end

    if down==false and up==false then
      if number < prev then down = true
      elseif number > prev then up = true
      else return false end
    end

    if up then
      if prev > number then return false end
      local r=number-prev
      if r~=1 and r~=2 and r~= 3 then return false end
      prev = number
    end

    if down then
      if number > prev then return false end
      local r=prev-number
      if r~=1 and r~=2 and r~= 3 then return false end
      prev = number
    end

  ::continue::
  end
  return true
end

local file = io.open("2-input.txt", "r")

local safe = 0
local safe_one_skip = 0

for line in file:lines() do
  local numbers = line:gmatch("[^%s]+")
  local numbers_arr = {}
  for i in numbers do
    table.insert(numbers_arr, i)
  end

  if is_safe(numbers_arr) then
    safe = safe + 1
    safe_one_skip = safe_one_skip + 1
  else
    for i=1, #numbers_arr do
      local n = table.remove(numbers_arr, i)
      if is_safe(numbers_arr) then
        safe_one_skip = safe_one_skip + 1
        break
      end
      table.insert(numbers_arr, i, n)
    end
  end

end

file:close()
print("puzzle 1:", safe)
print("puzzle 2:", safe_one_skip)

-- 490
-- 536