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(11,16).
next(16,17).
next(17,18).
next(18,19).
next(19,20).
next(20,21).
next(21,22).
next(22,23).
next(23,24).
next(24,25).
next(22,26).
next(26,27).
next(27,28).
next(21,29).
next(29,30).
next(30,31).
next(31,32).
next(29,33).
next(33,34).
next(34,35).
next(35,36).
next(36,37).
next(37,38).
next(38,39).
next(35,40).
next(40,41).
next(41,42).
next(42,43).
doAt(startflow,4).
doAt(a4,6).
doAt(a16,8).
doAt(a17,9).
doAt(a5,10).
doAt(a25,11).
doAt(a9,12).
doAt(a7,13).
doAt(endflow,14).
doAt(a13,16).
doAt(a6,17).
doAt(a18,18).
doAt(a15,19).
doAt(a8,20).
doAt(a24,21).
doAt(a22,22).
doAt(a14,23).
doAt(endflow,24).
doAt(a23,26).
doAt(endflow,27).
doAt(a12,29).
doAt(a10,30).
doAt(endflow,31).
doAt(a11,33).
doAt(a2,34).
doAt(a3,35).
doAt(a21,36).
doAt(a1,37).
doAt(endflow,38).
doAt(a20,40).
doAt(a1,41).
doAt(endflow,42).
subsAt(a4,5).
subsAt(a16,7).
leftrightnexts(23,26).
leftrightnexts(36,40).
leftrightnexts(30,33).
leftrightnexts(22,29).
leftrightnexts(12,16).