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