computercraft build floor

term.write("Please enter the length of floor: ")
local l = tonumber(read())

term.write("Please enter the width of floor: ")
local w = tonumber(read())

local itemID = 1
for i = 1, w do
  for j = 1, l do
    turtle.select(itemID)
    while (turtle.getItemCount() == 0) do
      itemID = itemID + 1
      if itemID > 16 then
        break
      end
      turtle.select(itemID)
    end

    if itemID > 16 then
      break
    end

    turtle.placeDown()
    if j < l then
      turtle.forward()
    end
  end

  if i % 2 == 1 then
    turtle.turnLeft()
    turtle.forward()
    turtle.turnLeft()
  else
    turtle.turnRight()
    turtle.forward()
    turtle.turnRight()
  end
end