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