:-dynamic br/1.
br(0).
ispis2:-izmedju(I,1,50),izmedju(J,3,20),K is I+J,K<20,
        write(I),write(','),write(J),nl,br(X),
        X1 is X+1, retract(br(X)),asserta(br(X1)),fail.
ispis2.
ispis:-ispis2,br(X),write('Ima ih '),write(X),nl,
        retract(br(X)),asserta(br(0)).