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