delEven(L,D).
delEven([],[]).
delEven([a],[a]).
delEven([b,c],[b]).
delEven([d,e,f],[d,f]).
delEven([g,h,i,j],[g,i]).

delEven([X],[X]).
delEven([X,Y],[X]).
delEven([X,Y,Z],[X,Z]).
delEven([X,Y,Z,T],[X,Z]).

