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