a := (  1, 18,  2)(  3, 19, 34)(  4, 20, 35)(  5, 21, 36)(  6, 22, 37)
(  7, 23, 38)(  8, 24, 39)(  9, 25, 40)( 10, 26, 41)( 11, 27, 42)( 12, 28, 43)
( 13, 29, 44)( 14, 30, 45)( 15, 31, 46)( 16, 32, 47)( 17, 33, 48);