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