Build

while true do
 f = ture
   turtle.select(1)
   if turtle.compare() then
       turtle.turnLeft()
       f = false
   end
   turtle.select(2)
   if turtle.compare() then
        turtle.turnRight()
        f = false
   end
   turtle.select(3)
   if turtle.compare() then
        turtle.up()
        turtle.turnLeft()
        f = false
   end
   if f == ture then
        turtle.forward()
   end

   i = 4
   while i <= 16 do
       turtle.select(i)
       if turtle.placeDown() then break end
       i = i + 1
   end


os.sleep(0.1)
end