z1 := (3,5)(4,6)(8,12)(9,13)(11,15)(14,20)(16,19)(17,22)(18,23)(21,25)(24,30)
     (26,32)(27,34)(28,35)(29,37)(31,39)(33,41)(36,46)(38,48)(42,53)(43,44)
     (45,56)(49,59)(51,61)(58,67)(60,65)(62,66)(68,74)(69,72)(70,71)(73,76)
     (75,77);