local minFuelAmount = 200
while true do
if turtle.getFuelLevel() < minFuelAmount then
  turtle.select(9)
  turtle.refuel()
  turtle.select(1)
end
while not turtle.forward() do
  turtle.dig()
end
while not turtle.down() do
  turtle.digDown
end
turtle.select(1)
while not turtle.placeDown() do
  turtle.digDown()
end
turtle.up()
turtle.select(2)
if not turtle.placeDown() then
  break
end
end