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