бинарное дерево

tree_insert(X,empty,tr(X,empty,empty)).
tree_insert(X,tr(X,L,R),tr(X,L,R)):-!.
tree_insert(X,tr(K,L,R),tr(K,L1,R)):-X<K,!,tree_insert(X,L,L1).
tree_insert(X,tr(K,L,R),tr(K,L,R1)):-tree_insert(X,R,R1).
tree_gen(0,empty):-!.
tree_gen(N,T):-X is random(100)-50,N1 is N-1,tree_gen(N1,T1),tree_insert(X,T1,T).
tree_print(T):-print2(T,0).
print2(empty,_).
print2(tr(X,L,R),H):-H1 is H+2,print2(R,H1),tab(H),write(X),nl,print2(L,H1).
tree_sum(empty,0).
tree_sum(tr(X,L,R),N):-tree_sum(L,N1),tree_sum(R,N2),N is N1+N2+X.
tree_length(empty,0).
tree_length(tr(X,L,R),N):-X>0,tree_length(L,N1),tree_length(R,N2),N is N1+N2+1;
tree_length(L,N1),tree_length(R,N2),N is N1+N2.
 
start(N):-tree_gen(N,A),write(A),nl,tree_print(A),nl,
    write('Среднее арифметическое положительных вершин: '),
    tree_sum(A,S),write(S),tree_length(S,A),write(S).

count(Tree,R):-count(Tree,Sum,N),N>0,!,R is Sum/N.
count(_,0):-print('Нет положительных элементов').
 
count(empty, 0, 0).
count(tr(X,L,R),Sum,N):-X>0,!,count(L,SumL,NL),count(R,SumR,NR),
    Sum is SumL+SumR+X,N is NL+NR+1.
count(tr(_,L,R),Sum,N):-count(L,SumL,NL),count(R,SumR,NR),
    Sum is SumL+SumR,N is NL+NR.