count_occurrences(X,[],0).
count_occurrences(X,[X|Y],Z) :- count_occurrences(X,Y,Z1), Z is Z1+1.

count_occurrences(X,[_|Y],Z) :- count_occurrences(X,Y,Z).


ll([],0).

ll([_|Y],K) :- ll(Y,J), K is J + 1.


ws([]).
ws([X|Y]) :- put(X), ws(Y).