goal([2/2, 1/1, 1/2, 2/1]).
goal([3/3, 1/1, 1/2, 1/3, 2/1, 2/2, 2/3, 3/1, 3/2]).
goal([4/4, 1/1, 1/2, 1/3, 1/4, 2/1, 2/2, 2/3, 2/4, 3/1, 3/2, 3/3, 3/4, 4/1, 4/2, 4/3]).
%goal([X/X|Rest]) :-
%    L is X*X-1,
%    length(Rest, L),
%    sort(Rest, Rest).


solve(A, Solution) :-
    between(1, 25, I),
    solve(A, [A], I, Solution), !.

solve(_, _, 0, _) :- !,
    fail.
solve(State, Solution, _, Solution) :-
    goal(State), !.
solve(State, Visisted, D, Solution) :-
    succesor(State, NextState),
    \+ member(NextState, Visisted),
    D1 is D-1,
    solve(NextState, [NextState|Visisted], D1, Solution).