a := ( 2,40)( 3,28)( 4,33)( 5,37)( 6,15)( 7,31)( 8,10)( 9,36)(11,25)(12,35)
(13,16)(17,24)(18,30)(19,38)(20,26)(21,39)(22,32)(23,27)(29,34)(41,42);