print('How far should I go?')
distance = io.read()

for i=1, distance do
    turtle.dig() -- layer 1
    turtle.forward()
    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.digUp()

    turtle.up() -- layer 2
    turtle.dig()
    turtle.digUp()
    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.turnLeft()

    turtle.up()  -- layer 3
    turtle.dig()
    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.turnLeft()
    turtle.down()
    turtle.down()

    os.sleep(0)
    print('Refueling...')
    for slot = 1,16 do
        item = turtle.getItemDetail(slot)
        if item ~=nil and item['name'] == 'minecraft:coal' then
            turtle.select(slot)
        end
        while turtle.getFuelLevel() <= 800 do
            if turtle.refuel() then
                print('Fuel level is: ' .. turtle.getFuelLevel())
            else
                print('Not enough fuel')
                break
            end
        end
    end
end
turtle.turnLeft() -- Return home
turtle.turnLeft()
for c=1, distance do
    turtle.forward()
end