vypis([]).
vypis([H|T]):- writeln(H),vypis(T).

sum([],0).
sum([H|T],S) :- sum(T, X), S is H+X.


app(L,[],[L]).
app(L,[H|T],[H|X]):- app(L,T,X). 


reverse([], []).
reverse([H|T], X) :- reverse(T,Y), app(H,Y,X).


lrev(L1, L2) :- lrev1(L1, [], L2).

lrev1([],L, L).
lrev1([H|T], A, B) :- lrev1(T, [H|A], B).

zip([], [], []).
zip([H1|T1],[H2|T2], [[H1,H2]|Out]) :- zip(T1, T2, Out).


heads([],[]).
heads([[H|_]|TS],[H|X] ) :- heads(TS,X).
tails([],[]).
tails([[_|T]|TS],[T|X] ) :- tails(TS,X).

emptys([]).
emptys([ [] | T]) :- emptys(T).

transp(E,[]):-emptys(E).
transp(M , [H|V]):- heads(M,H),tails(M,T),transp(T,V).