next(1,2).
next(2,3).
next(3,4).
next(4,5).
next(5,6).
next(6,7).
next(7,8).
next(8,9).
next(9,10).
next(10,11).
next(11,12).
next(12,13).
next(13,14).
next(14,15).
next(15,16).
next(13,17).
next(17,18).
next(18,19).
next(19,20).
next(20,21).
next(21,22).
next(22,23).
next(20,24).
next(24,25).
next(25,26).
next(26,27).
next(27,28).
next(25,29).
next(29,30).
next(30,31).
next(31,32).
next(24,33).
next(33,34).
next(17,35).
next(35,36).
next(36,37).
next(37,38).
next(38,39).
next(39,40).
next(40,41).
next(41,42).
next(42,43).
next(40,44).
next(44,45).
next(45,46).
next(46,47).
next(47,48).
next(45,49).
next(49,50).
next(50,51).
next(51,52).
next(44,53).
next(53,54).
doAt(startflow,3).
doAt(a3,5).
doAt(a16,6).
doAt(a13,7).
doAt(a19,8).
doAt(a17,9).
doAt(a14,10).
doAt(a15,11).
doAt(a5,12).
doAt(a12,13).
doAt(a23,14).
doAt(endflow,15).
doAt(a22,17).
doAt(a21,18).
doAt(a25,19).
doAt(a2,20).
doAt(a11,21).
doAt(endflow,22).
doAt(a4,24).
doAt(a20,25).
doAt(a24,26).
doAt(endflow,27).
doAt(a7,29).
doAt(a9,30).
doAt(endflow,31).
doAt(endflow,33).
doAt(a1,35).
doAt(a6,36).
doAt(a10,37).
doAt(a18,38).
doAt(a25,39).
doAt(a2,40).
doAt(a11,41).
doAt(endflow,42).
doAt(a4,44).
doAt(a20,45).
doAt(a24,46).
doAt(endflow,47).
doAt(a7,49).
doAt(a9,50).
doAt(endflow,51).
doAt(endflow,53).
subsAt(a3,4).
leftrightnexts(26,29).
leftrightnexts(25,33).
leftrightnexts(21,24).
leftrightnexts(46,49).
leftrightnexts(45,53).
leftrightnexts(41,44).
leftrightnexts(18,35).
leftrightnexts(14,17).