a21 := (1,3,2,4)(5,7,10,15)(6,8,12,18)(9,13,20,27)(11,16,23,32)(14,21,29,40)
     (17,24,34,46)(19,25,36,49)(22,30,42,56)(26,37,31,43)(28,39,33,45)(35,47,
     62,81)(38,51,67,89)(41,54,71,96)(44,58,76,104)(48,63,83,115)(50,65,86,
     120)(52,68,91,127)(53,69,93,129)(55,72,98,135)(57,74,101,140)(59,77,106,
     147)(60,78,108,109)(61,79,110,149)(64,84,117,158)(66,87,122,165)(70,94,
     130,174)(73,99,137,182)(75,102,142,168)(80,111,151,197)(82,113,154,199)
     (85,118,160,205)(88,123,114,155)(90,125,169,212)(92,128,173,217)(95,131,
     176,220)(97,133,179,222)(100,138,184,228)(103,143,134,162)(105,145,190,
     235)(107,148,194,240)(112,152,132,177)(116,156,200,227)(119,161,207,250)
     (121,163,209,252)(124,167,211,188)(126,170,214,258)(136,180,223,204)(139,
     185,230,271)(141,186,232,273)(144,189,234,166)(146,191,237,279)(150,159,
     203,247)(153,198,244,286)(157,201,196,242)(164,210,254,295)(171,202,192,
     225)(172,215,259,299)(175,183,226,268)(178,221,265,305)(181,224,219,263)
     (187,233,275,314)(193,238,280,318)(195,241,284,243)(206,249,291,248)(208,
     251,231,272)(213,257,261,301)(216,260,300,329)(218,262,303,264)(229,270,
     310,269)(236,278,282,320)(239,281,319,337)(245,287,322,292)(246,288,323,
     298)(253,293,327,283)(255,296,294,304)(256,297,328,344)(266,306,331,311)
     (267,307,332,317)(274,312,335,302)(276,315,313,285)(277,316,336,348)(289,
     324,341,350)(290,325,342,351)(308,333,346,352)(309,321,339,349)(326,338,
     334,330)(340,343,345,347);