Rubber

local function refuel()
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel > 0 then
        return
    end
    local function tryRefuel()
        for n=15,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    turtle.select(1)
                    return true
                end
            end
        end
        turtle.select(1)
        return false
    end
    if not tryRefuel() then
        print( "Add more fuel to continue." )
        while not tryRefuel() do
            sleep(1)
        end
        print( "Resuming." )
    end
end


local function tryUp()
    refuel()
    while not turtle.up() do
        if turtle.detectUp() then
            if not tryDigUp() then
                return false
            end
        elseif turtle.attackUp() then
            collect()
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function tryDown()
    refuel()
    while not turtle.down() do
        if turtle.detectDown() then
            if not tryDigDown() then
                return false
            end
        elseif turtle.attackDown() then
            collect()
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function tryForward()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            if not tryDig() then
                return false
            end
        elseif turtle.attack() then
            collect()
        else
            sleep( 0.5 )
        end
    end
    return true
end

write("Wie breit ist der Baum? : ")
bb=io.read()
bb=bb+0
write("Wie lange ist der Baum? : ")
ll=io.read()
ll=ll+0
write("Wie hoch ist der Baum? : ")
hh=io.read()
hh=hh+0

bb2=0
ll2=ll
hh2=hh
hn = 0
ln = 0
bn=0

while bb < bb2 do
    while ll > 0 do
        while hn < hh do
         tryUp()
         hn=hn+1
        end
        hn = 0
        tryForward()
        while hn < hh do
         tryDown()
         hn=hn+1
        end
        hn = 0
        tryForward()
        ll=ll-2
    end
    turtle.turnLeft()
bb2=bb2+1
end