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