Tree Turtle 2.0

turtle.refuel(4)
print("Starting...")

i = 0
a = 0
while turtle.detectUp() do
                if turtle.getFuelLevel() < 10 then
                        turtle.refuel(4)
                end

        turtle.digUp()
        turtle.up()
        i = i+1

end
        while i > a do
                if turtle.getFuelLevel() < 10 then
                        turtle.refuel(4)
                end

                turtle.down()
                a = a+1
        end