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