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