#N the barber pole
#C period 2 oscillator discovered by the MIT group
#R
 -6  -6
 -5  -6
 -6  -5
 -4  -5
 -4  -3
 -2  -3
 -2  -1
  0  -1
  0   1
  2   1
  2   3
  4   3
  4   5
  6   5
  5   6
  6   6