turtle.refuel()
print("refuel")
DEPTH = 0
local function checkAround()
  i = 0
  turtle.select(2)
  while i<4 do
    if not turtle.compare() then
      turtle.dig()
    end
    turtle.turnLeft()
    i = i+1
  end
  turtle.select(1)
end

local function getBackUp()
  while DEPTH do
    turtle.up()
    DEPTH = DEPTH - 1
  end
end


while true do
  checkAround()
  if turtle.digDown() then
    turtle.down()
    DEPTH = DEPTH + 1
  else
    getBackUp()
end