% 32.1
DOMAINS
i=integer
list=i*

PREDICATES
nondeterm append(list, list, list)
nondeterm odd_append(list, list, list)
nondeterm odd_elements(list,list)
nondeterm enter(list)
nondeterm getlength(list,i)
nondeterm run
nondeterm do(char)
nondeterm check(i,i,list,list)

CLAUSES
append([], List2, List2).
append([Head|Tail], List2, [Head|TailResult]):-
append(Tail, List2, TailResult).

enter([H|T]):-
write("Enter the element of the list or type 'END': "),
readint(H),
enter(T).
enter([]):-!.

getlength([],N):-N=0.
getlength([_|T],N):-
getlength(T,NewN),N=NewN+1.

check(N,N1,L,L1):-
N1<>N,write("Bad value"),nl;
odd_append(L, L1, NewL),write("Your new list is ",NewL),nl.

odd_elements([],[]).
odd_elements([X],[X]).
odd_elements([B, _|Tail], [A|OddTail]):-
A=B,
odd_elements(Tail, OddTail).

odd_append(A, B, Appended):-
odd_elements(A, AOdd),
odd_elements(B, BOdd),
append(AOdd, BOdd, Appended).

run:-
write("*******ENTER*******"), nl,
write("- 1 to START"),nl,
write("- 0 to EXIT"),nl,
write("***********************"),nl,
write(">>"), readchar(X),
write(X), nl, do(X), run.

do('1'):-
enter(L),write("Your list 1 is ",L),nl,
getlength(L,N),enter(L1),
write("Your list 2 is ",L1),nl,
getlength(L1,N1),check(N,N1,L,L1).

do('0'):-
write("That's all"),exit.

do(_):-
write("Bad value"), nl.
goal
run.