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