odd_calc(List,Return):-
	plus(List,Return),!.

plus([V],V).
plus([H|T],RV):-
	minus(T,PRV),
	RV is PRV+H.
minus([V],RV):- RV is -V.
minus([H|T],RV):-
	plus(T,PRV),
	RV is PRV-H.