X ( 2 , 21 , 3 , 22 ) X ( 4 , 20 , 5 , 19 ) X ( 5 , 15 , 6 , 14 ) X ( 8 , 1 , 9 , 2 ) X ( 10 , 4 , 11 , 3 ) X ( 12 , 14 , 7 , 13 ) X ( 15 , 1 , 16 , 6 ) X ( 16 , 8 , 17 , 7 ) X ( 18 , 11 , 19 , 12 ) X ( 20 , 10 , 21 , 9 ) X ( 22 , 18 , 13 , 17 ) {\displaystyle X(2,21,3,22)X(4,20,5,19)X(5,15,6,14)X(8,1,9,2)X(10,4,11,3)X(12,14,7,13)X(15,1,16,6)X(16,8,17,7)X(18,11,19,12)X(20,10,21,9)X(22,18,13,17)}