local function tryMove()
  while turtle.getFuelLevel() == 0 do
    for i = 1, 16 do
      turtle.select(i)
      if turtle.refuel(1) then
        break
      end
    end
  end
end

local function tryMoveForward()
  tryMove()
  turtle.forward()
end

local function tryMoveLeft()
  turtle.turnLeft()
end

local function tryMoveRight()
  turtle.turnRight()
end

local function tryPlaceUp()
  while not turtle.placeUp() do
    local i = turtle.getSelectedSlot()
    i = i + 1
    if i > 16 then
      i = 1
    end
    turtle.select(i)
  end
end

for a = 1, 127 do
tryPlaceUp()
for b = 1, 255 do
tryMoveForward()
tryPlaceUp()
end
tryMoveRight()
tryMoveForward()
tryMoveRight()
tryPlaceUp()
for b = 1, 255 do
tryMoveForward()
tryPlaceUp()
end
tryMoveLeft()
tryMoveForward()
tryMoveLeft()
end
