function Dig(str)
    for i=1,str do
        turtle.dig()
        turtle.forward()
    end
    turtle.turnRight()
end

function Down()
    turtle.digDown()
    turtle.down()
end

str = 0
while true do
    if str == 0 then
        Down()
        str = 9
    end
    for i=1,3 do
        Dig(str)
    end
    str = str - 1
    print(turtle.getFuelLevel())
    if turtle.getFuelLevel() == 0 then
        turtle.refuel()
    end
end