count_occ([], []).
count_occ([H|T], R) :-
    count_occ(T, Temp),
    increment(Temp, H, R).

increment([], E, [[E,1]]).
increment([[H,C]|T], H, [[H,CplusOne]|T]) :-
    CplusOne is C + 1.
increment([[H,C]|T], E, [[H,C]|R]) :-
    H \= E,
    increment(T, E, R).
    
:- count_occ([a,b,b,a,c,d,a,b,e,b,d,c], R), writeln(R).