mysetof(X,P,S) :- mysetof(X,P,[],S),                  !.mysetof(X,P,ACC,ACC) :- not(new_element(X,P,ACC)),                        !.mysetof(X,P,ACC,S) :- subst(X,Y,P,Q),                      new_element(X,P,ACC),                      append(ACC,[X],ACC1),                      mysetof(Y,Q,ACC1,S).new_element(X,P,S) :- call(P),                      not(member(X,S)).subst(_,_,P,P) :- atomic(P),                  !.subst(X,Y,P,Y) :- P == X,                  !.subst(_,_,P,P) :- var(P),                  !.subst(X,Y,P,Q) :- P =.. [PFUN|PARG],                  subst_list(X,Y,PARG,QARG),                  Q =.. [PFUN|QARG].subst_list(_,_,[],[]).subst_list(X,Y,[PH|PTAIL],[QH|QTAIL]) :- subst(X,Y,PH,QH),                                         subst_list(X,Y,PTAIL,QTAIL).not(P) :- call(P),          !,          fail.not(_).member(X,[X|_]).member(X,[_|T]) :- member(X,T).append([],L,L).append([H|TAIL],L2,[H|NEWTAIL]) :- append(TAIL,L2,NEWTAIL).p(0).p(1).p(2).p(0).p(2).p(3).