21,19,20,0,3,1,2,5,4,39,40,38,11,10,12,49,48,43,30,6,7,9,8,13,15,14,32,31,33,41,42,23,24,22,26,25,35,36,37,34,47,46,44,45,18,17,16,27,29,28