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