startup

function go()
  while not turtle.forward() do
    os.sleep(0.3)
  end
end
function goBack()
  while not turtle.back() do
    os.sleep(0.3)
  end
end
function goUp()
  while not turtle.up() do
    os.sleep(0.3)
  end
end
function goDown()
  while not turtle.down() do
    os.sleep(0.3)
  end
end
function fuel()
  while turtle.getFuelLevel() < 200 do
    turtle.select(2)
    turtle.suckDown(1)
    turtle.refuel()
  end
end

fuel()
turtle.select(16)
if turtle.compareDown() then
  if not turtle.detect() then
    turtle.select(1)
    turtle.drop()
    go()
    turtle.suck(1)
    goBack()
    turtle.place()
  end
else
  turtle.up()
  turtle.select(15)
  if turtle.compareUp() then
    turtle.select(1)
    turtle.digUp()
    goUp()
    while turtle.compareUp() do
      turtle.digUp()
      goUp()
    end
  end
  turtle.drop()
  while not turtle.detectDown() do
    goDown()
  end
  turtle.suck(1)
  goBack()
  turtle.place()
end

while true do
  os.sleep(10)
  turtle.select(15)
  if turtle.compare() then
    fuel()
    turtle.select(1)
    turtle.dig()
    go()
    while turtle.compareUp() do
      turtle.digUp()
      goUp()
    end
    turtle.drop()
    while not turtle.detectDown() do
      goDown()
    end
    turtle.suck(1)
    goBack()
    turtle.place()
  end
end