z1 := (2,4)(3,6)(5,9)(7,12)(8,13)(10,14)(11,16)(15,20)(17,22)(18,24)(19,25)
     (21,28)(23,30)(27,34)(29,37)(31,39)(33,40)(35,42)(36,44)(38,47)(41,52)
     (43,55)(45,48)(46,57)(49,60)(50,61)(51,63)(53,66)(54,68)(56,70)(58,73)
     (59,75)(62,77)(64,80)(65,82)(67,85)(69,87)(71,90)(72,91)(74,93)(76,96)
     (78,98)(79,99)(81,102)(83,103)(84,105)(86,108)(88,110)(89,112)(92,116)
     (94,118)(95,120)(97,121)(100,125)(101,127)(104,107)(106,130)(109,134)
     (111,137)(113,139)(114,140)(115,142)(119,136)(124,146)(126,149)(128,150)
     (129,151)(131,152)(133,154)(135,147)(138,157)(141,158)(143,159)(144,160)
     (145,161)(148,163)(155,166)(156,167)(162,171)(164,173)(168,170)(169,175);