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