relative_x = 0
relative_y = 0
rotation = 0

function rotateTo(targetRotation)
  while rotation % 4 ~= targetRotation do
    turtle.turnRight()
    rotation = rotation + 1
  end

  rotation = rotation % 4
end


function goTo(x, y)
  if x ~= relative_x then
    if x > relative_x then
      rotateTo(1)
    else
      rotateTo(3)
    end

    while x ~= relative_x do
      turtle.dig()
      assert(turtle.forward())

      if x > relative_x then
        relative_x = relative_x + 1
      else
        relative_x = relative_x - 1
      end
    end
  end

  if y ~= relative_y then
    if y > relative_y then
      rotateTo(0)
    else
      rotateTo(2)
    end

    while y ~= relative_y do
      while true do
        local exists, _ = turtle.inspect()

        if exists then
          if not turtle.dig() then
            break
          end
        else
          break
        end
      end

      assert(turtle.forward())

      if y > relative_y then
        relative_y = relative_y + 1
      else
        relative_y = relative_y - 1
      end
    end
  end
end

for y = 0,20 do
  for x = 0,4 do
    if x % 2 == 0 then
      goTo(x, 0)
      goTo(x, 4)
    else
      goTo(x, 4)
      goTo(x, 0)
    end

    for slot = 1,16 do
      turtle.select(slot)
      detail = turtle.getItemDetail()

      if detail ~= nil then
        turtle.refuel(64)

        if not string.find(detail["name"], "ore") and not string.find(detail["name"], "raw") and not string.find(detail["name"], "diamond") then
          turtle.drop(64)
        end
      end
    end
  end

  goTo(0, 0)
  rotateTo(2)

  for i = 1,y do
    turtle.up()
  end

  for slot = 1,16 do
    turtle.select(slot)
    turtle.drop(64)
  end

  for i = 1,y do
    turtle.down()
  end

  rotateTo(0)

  if y ~= -40 then
    turtle.digDown()
    assert(turtle.down())
  end
end