a := ( 1,25)( 2,54)( 3,18)( 4,22)( 5,23)( 6,53)( 7,32)( 8,40)( 9,24)(10,41)
(11,35)(12,51)(13,48)(14,31)(15,28)(16,44)(17,38)(19,39)(20,47)(21,26)(29,33)
(30,42)(34,36)(37,49)(43,45)(46,50);