brisi(X,[X|Y],Y).
brisi(X,[Y|Z],[Y|U]):-brisi(X,Z,U).

elem1(X,Y):-brisi(X,Y,Z).
dodaj(X,L,L1):-brisi(X,L1,L).
redjaj(L):-brisi(X,L,L1),
            write(X),write(':'),write(L1),nl,fail.