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(7,13).
next(13,14).
next(14,15).
next(15,16).
next(16,17).
next(17,18).
next(18,19).
next(14,20).
next(20,21).
next(21,22).
next(22,23).
next(23,24).
next(24,25).
next(25,26).
next(26,27).
next(27,28).
next(28,29).
doAt(startflow,4).
doAt(a11,6).
doAt(a10,7).
doAt(a15,8).
doAt(a6,9).
doAt(a3,10).
doAt(endflow,11).
doAt(a14,13).
doAt(a8,14).
doAt(a13,15).
doAt(a6,16).
doAt(a3,17).
doAt(endflow,18).
doAt(a9,20).
doAt(a12,21).
doAt(a5,22).
doAt(a7,23).
doAt(a1,24).
doAt(a4,25).
doAt(a6,26).
doAt(a3,27).
doAt(endflow,28).
subsAt(a11,5).
leftrightnexts(15,20).
leftrightnexts(8,13).