[1,3,2,4,5,7,6,8,9,11,10,12,13,15,14,16,17,19,18, 20,21,23,22,24,25,27,26,28,29,31,30,32,33,35,34, 36,37,39,38,40,41,43,42,44,45,47,46,48,49,51,50, 52,53,55,54,56,57,59,58,60,61,63,62,64,65,67,66, 68]