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(10,15).
next(15,16).
next(16,17).
next(17,18).
next(18,19).
next(19,20).
next(20,21).
next(21,22).
next(17,23).
next(23,24).
next(24,25).
next(25,26).
next(26,27).
next(27,28).
next(28,29).
next(29,30).
next(30,31).
doAt(startflow,6).
doAt(a1,8).
doAt(a9,9).
doAt(a2,10).
doAt(a10,11).
doAt(a13,12).
doAt(endflow,13).
doAt(a15,15).
doAt(a4,16).
doAt(a11,17).
doAt(a7,18).
doAt(endflow,21).
doAt(a8,23).
doAt(a14,24).
doAt(a3,25).
doAt(a12,27).
doAt(a5,28).
doAt(endflow,30).
compAt(a1,x28,7).
compAt(a10,x7,19).
compAt(a10,x23,20).
compAt(a10,x7,26).
compAt(a10,x23,29).
leftrightnexts(18,23).
leftrightnexts(11,15).