Tree Turtle

turtle.refuel()
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