X ( 1 , 29 , 2 , 28 ) X ( 2 , 16 , 3 , 15 ) X ( 5 , 33 , 6 , 32 ) X ( 6 , 20 , 7 , 19 ) X ( 9 , 37 , 10 , 36 ) X ( 10 , 24 , 11 , 23 ) X ( 13 , 1 , 14 , 40 ) X ( 14 , 28 , 15 , 27 ) X ( 17 , 5 , 18 , 4 ) X ( 18 , 32 , 19 , 31 ) X ( 21 , 9 , 22 , 8 ) X ( 22 , 36 , 23 , 35 ) X ( 25 , 13 , 26 , 12 ) X ( 26 , 40 , 27 , 39 ) X ( 29 , 17 , 30 , 16 ) X ( 30 , 4 , 31 , 3 ) X ( 33 , 21 , 34 , 20 ) X ( 34 , 8 , 35 , 7 ) X ( 37 , 25 , 38 , 24 ) X ( 38 , 12 , 39 , 11 ) {\displaystyle X(1,29,2,28)X(2,16,3,15)X(5,33,6,32)X(6,20,7,19)X(9,37,10,36)X(10,24,11,23)X(13,1,14,40)X(14,28,15,27)X(17,5,18,4)X(18,32,19,31)X(21,9,22,8)X(22,36,23,35)X(25,13,26,12)X(26,40,27,39)X(29,17,30,16)X(30,4,31,3)X(33,21,34,20)X(34,8,35,7)X(37,25,38,24)X(38,12,39,11)}