member_set(X, [H|T]) :- X = H.
member_set(X, [H|T]) :- X \= H, member_set(X, T).

insert_elem_set(X, S1, S1) :- member_set(X, S1).
insert_elem_set(X, S1, [X|S1]) :- \+ member_set(X, S1).

head([H|T], H).

delete_elem_set(X, [X|T1], T1).
delete_elem_set(X, [H1|T1], [H1|T2]) :- delete_elem_set(X, T1, T2).

empty_set([]).


prog:-

	readNums([],0).

readNums(Set, 4):-
	head(Set, H),
	delete_elem_set(H, Set, T),
	findMaX(T, H).

readNums(Set, Cnt):-
	nl,
	write("dose arithmo"),
	read(Num),
	insert_elem_set(Num, Set, NSet),
	Ncnt is Cnt+1,
	readNums(NSet, Ncnt).

findMaX([], MaX):-
	write(MaX).

findMaX(Set, MaX):-
	head(Set, H),
	H > MaX,
	delete_elem_set(H, Set, T),
	findMaX(T, H).

findMaX(Set, MaX):-
	head(Set, H),
	H =< MaX,
	delete_elem_set(H, Set, T),
	findMaX(T, MaX).