go(Start,Dest,Route,Dist) :-
    go4([r(0,[Start])],Dest,R,R1,Dist),
    reverse(R1,Route).
a(n,k,38). a(k,p,23). a(d,n,40). a(p,d,52). a(w,k,33). a(w,p,39).
go4(Routes,Dest,Route,R1,Dist) :-
    shortest(Routes,Shortest,RestRoutes,Dist),
    proceed(Shortest,Dest,RestRoutes,Route,R1,Dist).
proceed(r(Dist,Route),Dest,_,Route1,R1,Dist1) :-
    Route=[Dest|_],Dist1=Dist,R1=Route.
proceed(r(Dist,[Last|Trail]),Dest,Routes,Route,R1,Dist1) :-
    findall(r(D1,[Z,Last|Trail]),
        legalnode(Last,Trail,Z,Dist,D1),List),
    append(List,Routes,NewRoutes),
    go4(NewRoutes,Dest,Routes,R1,Dist1).
shortest([Route|Routes],Shortest,[Route|Rest],Dist) :-
    shortest(Routes,Shortest,Rest,Dist),
    shorter(Shortest,Route),!.
shortest([Route|Rest],Route,Rest,Dist).
shorter(r(M1,_),r(M2,_)) :- M1<M2.
legalnode(X,Trail,Y,Dist,NewDist) :-
    (a(X,Y,Z) ; a(Y,X,Z)),
    not(member(Y,Trail)),
        NewDist is Dist+Z.
run:-
   go(Start,Dest,Route,Dist),
   print(Start),
   nl,
   print(Dest),
   nl,
   print(Route),
   nl,
   print(Dist).