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is_odd(X) :- 1 is mod(X,2).
is_even(X) :- 0 is mod(X,2).

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number(s(0)).
number(s(s(X))):-number(X).

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is_even(X) :- 0 is mod(X,2).

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 even(N) :- (N mod 2 =:= 0
 ->print('EVEN')
 ;print('ODD')
 ).
 

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comp(A,B) :- A is B.
odd(N) :- comp(N mod 2, 1).

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is_even(X) :- 0 is mod(X,2).

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even(0).
even(s(s(X))):-even(X)
 
odd(s(0)).
odd(s(s(X))):-odd(X)

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even(X):-X mod 2 is 0.

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Odd_even(X).
mod(X,2) == 0.

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is_odd(X) :- 1 is mod(X,2).
is_even(X) :- 0 is mod(X,2).

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?- write('hi').

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number(0).
number(X) :- mod(X,2) is 0.

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write('Hello world!').

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odd(X) :- rem(X,2) is 1.

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number(s(X)).
number(s(s(X))):-number(X).

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is_odd(X) :- 1 is mod(X,2).
is_even(X) :- 0 is mod(X,2).

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?- write(X).

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number(0).
number(0) :- mod(X,2) is 0.

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comp(A,B) :- A is B.
odd(C,N) :- comp(N mod 2, 1).

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get0(X), n1,
(
even(X), print( 'even'), n1, fail)
;
(print( 'blah' ), n1, fail )

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oddEven(X, RET) :-
        X > 0,
        V is mod(X,2),
        V == 0,
                write('even'),
        V == 1,
                write('odd'),
        RET is V.

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countdown(X).
?- write(X).

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countdown(0) :- !.
countdown(X) :-
        number(X),
        X < 0.
countdown(X) :-
        number(X),
        X>=0,
        write(X), nl,
        NX is X-1,

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is_even(X) :- 0 is mod(X,2).

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c(0):-!.
c(X):-
        write(X), n1,
        succ(XN,X),
        c(XN).

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Odd_even(X):- mod(X,2), write ('even number'), nl.
Odd_even(X):- write ('odd number'), nl.

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is_odd(X) :- mod(X,2) is 1.
is_even(X) :- mod(X,2) is 0.

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is_odd(X) :- mod(X,2) is 1.
is_even(X) :- mod(X,2) is 0.

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oddEven(X, RET) :-
        X > 0,
        V is mod(X,2),
        V == 0,
                write('even'),
        V == 1,
                write('odd'),
        RET is V.

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number(s(0)).
number(s(s(X))):-number(X).