Fuel stack

-- pastebin get EkYnFWAk fuel
first = turtle.getFuelLevel()
turtle.refuel(1)
second = turtle.getFuelLevel()
unit = second - first

while turtle.getFuelLevel() < 19990 - unit do
    turtle.refuel()
    if turtle.getItemCount() == 0 then
        break
    end
end
print(turtle.getFuelLevel())