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