[0,1,1,2,2,3,3,4,3,4,4,5,5,6,6,7,5,6,6,7,7,8,8,9, 8,9,9,10,10,11,11,12,8,9,9,10,10,11,11,12,11,12, 12,13,13,14,14,15,13,14,14,15,15,16,16,17,16,17, 17,18,18,19,19,20,13,14,14,15,15,16,16,17,16,17, 17,18,18,19,19,20]