%Consecutive quadruple's with the same product.
removeUniques([[X,Y,S,P],[X1,Y1,S1,P]|R], L, O):-
	removeUniques(R, [[X,Y,S,P],[X1,Y1,S1,P]|L], O).
%Compare quadruple product with head of new output list, to double check for uniques.
removeUniques([[X,Y,S,P]|R], [[X1,Y1,S1,P]|L], O):-
	removeUniques(R, [[X,Y,S,P],[X1,Y1,S1,P]|L], O).
%Unique, skip.
removeUniques([[X,Y,S,P],[X1,Y1,S1,P1]|R], L, O):-
	removeUniques([[X1,Y1,S1,P1]|R], L, O).
%One element left.
removeUniques([[X,Y,S,P]|R], L, O) :- 
	removeUniques(R, L, O).
%Base case
removeUniques([], L, L).

%Consecutive quadruple's with the same product.
sortUniques([[X,Y,S,P],[X1,Y1,S1,P]|R], L, O, L2, A):-
	sortUniques(R, [[X,Y,S,P],[X1,Y1,S1,P]|L], O, L2 ,A).
%Compare quadruple product with head of new output list, to double check for uniques.
sortUniques([[X,Y,S,P]|R], [[X1,Y1,S1,P]|L], O, L2, A):-
	sortUniques(R, [[X,Y,S,P],[X1,Y1,S1,P]|L], O, L2, A).
%Unique, skip.
sortUniques([[X,Y,S,P],[X1,Y1,S1,P1]|R], L, O, L2, A):-
	sortUniques([[X1,Y1,S1,P1]|R], L, O, [[X,Y,S,P]|L2], A).
%One element left.
sortUniques([[X,Y,S,P]|R], L, O, L2, A) :- 
	sortUniques(R, L, O, [[X,Y,S,P]|L2], A).
%Base case
sortUniques([], L, L, A, A).