Translation to DCG Semicontext not working

Question

Since this question uses list, I wanted to solve it using DCG. In the process I realized that semicontext could be used. (DCG Primer)

The original problem is to return c

Answer 1

An alternative solution that doesn't require push-back lists or lookahead:

count_dcg(N0,N) -->
    [C], {N1 is N0 + 1}, count_dcg(N1,N,C).
count_dcg(N,N) -->
    [].

count_dcg(N0,N,C) -->
    [C],
    count_dcg(N0,N,C).
count_dcg(N0,N,C) -->
    [C1],
    {C \== C1, N1 is N0 + 1},
    count_dcg(N1,N,C1).
count_dcg(N,N,_) -->
    [].

count(L,N) :-
    phrase(count_dcg(0,N),L).