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