my_append(L1,L2,Res) :-
	L1 = [],
	Res = L2.

my_append(L1,L2,Res) :-
	L1 = [H|T],
	my_append(T,L2,R),
	Res = [H|R].

inc0(X,N) :- N = X+1.
inc1(X,N) :- N is X+1.

len([],0).
len([_|T], N) :-
	len(T,A),
	N is A+1.

max_of_list([X],X).

max_of_list([H|T], Max) :-
    max_of_list(T,M),
    H > M,
    Max = H.

max_of_list([H|T], Max) :-
    max_of_list(T,M),
    H =< M,
    Max = M.

?- use_module(library(clpfd)).

puzzle([S,E,N,D] + [M,O,R,E] = [M,O,N,E,Y]) :-
        Vars = [S,E,N,D,M,O,R,Y],
        Vars ins 0..9,
        all_different(Vars),
	             S*1000 + E*100 + N*10 + D
	           + M*1000 + O*100 + R*10 + E
	#= M*10000 + O*1000 + N*100 + E*10 + Y,
        M #\= 0,
	S #\= 0.

p(a).
p(b).
q(x).
q(y).

r(0,0).
r(X,Y) :- p(X), q(Y).
r(1,2).


p1(X,Y) :-
	X > Y.

p2(X,Y) :-
	[X,Y] ins -1000 .. 1000,
	X #> Y.


all_sum_equal([], _).
all_sum_equal([H|T], N) :-
	sum_equal(H,N),
	all_sum_equal(T,N).

sum_equal([],0).
sum_equal([H|T], N) :-
	sum_equal(T,M),
	N #= H+M.

carre_magique(Vars,N) :-
	Vars = [A,B,C,
		D,E,F,
		G,H,I],
	Rows = [[A,B,C], [D,E,F], [G,H,I]],
	Cols = [[A,D,G], [B,E,H], [C,F,I]],
	Diag = [[A,E,I], [G,E,C]],
	Vars ins 1 .. 9,
	all_different(Vars),
	all_sum_equal(Rows,N),
	all_sum_equal(Cols,N),
	all_sum_equal(Diag,N).