wall

io.write("Length of the wall : ")
length = io.read()
io.write("Height of the wall : ")
height = io.read()

turtle.up()
turtle.select(1)

for h=0,height do
  for l=0,length do
    if turtle.detectDown() then
      turtle.digDown()
    end
    turtle.placeDown()
    turtle.forward()
  end
  turtle.up()
  halfturn()
end