[1,2,3,3,4,4,4,5,5,5,6,6,7,7,7,8,8,8,8,8,9,9,9,10, 10,10,11,11,11,12,12,12,12,12,12,13,13,13,14,14, 14,15,15,15,15,15,15,16,16,16,16,16,16,16,17,17, 17,18,18,18,19,19,19,20,20,20,20,20,20,20,20,20, 21,21]