function checkUp()
    local needFuel = 0
    local needTorch = 0
    local needEmpty = 0

    if turtle.getFuelLevel() < 10 then
        needFuel = 1
    end
    if turtle.getItemCount(4) == 0 then
        needTorch = 1
    end
    if turtle.getItemCount(16) > 0 then
        needEmpty = 1
    end

    if needFuel == 1 or needTorch == 1 or needEmpty == 1 then
        turtle.turnRight()
        turtle.turnRight()
    else
        return
    end
    if needFuel == 1 then
        turtle.select(1)
        turtle.place()
        turtle.suck()
        turtle.refuel()
        turtle.dig()
    end
    if needTorch == 1 then
        turtle.select(2)
        turtle.place()
        turtle.select(4)
        turtle.suck()
        turtle.select(2)
        turtle.dig()
    end
    turtle.select(3)
    turtle.place()
    for i = 5, 16 do
        turtle.select(i)
        turtle.drop()
    end
    turtle.select(3)
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    return
end

local dist = 30
for i = 0, dist do
    while turtle.detect() do
        turtle.dig()
        checkUp()
    end
    turtle.forward()
    while turtle.detectUp() or turtle.detectDown() do
        turtle.digUp()
        checkUp()
        turtle.digDown()
        checkUp()
    end
    turtle.forward()
end