z1 := (1,2)(3,7)(4,8)(5,9)(6,10)(11,19)(12,20)(13,21)(14,18)(15,22)(16,23)(17,
     24)(25,37)(26,32)(27,38)(28,34)(29,39)(30,40)(31,41)(33,42)(35,43)(36,44)
     (45,47)(46,48);