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