z1 := (2,4)(3,5)(6,10)(7,11)(8,12)(9,13)(14,20)(15,21)(16,18)(19,22)(23,28)
     (24,29)(25,30)(26,31)(27,32)(33,41)(34,42)(35,43)(36,44)(37,45)(38,39)
     (40,46)(47,56)(48,57)(49,58)(50,59)(52,60)(53,61)(54,62)(63,64);