I'm trying to create a rule `F(C,L)` where `C` and `L` are integer lists. `L` contains the index number (starting from 1) of all the elements of `C` that are equal to `43`. My code is shown below. When I try `F([43,42,43,42,42,43],L)`. it returns true. What have I done wrong? Thanks in advance!

```
F(C,L) :-
    forall(
        (
            member(X,C),
            X=43,
            nth1(N,C,X)
        ),
        member(N,L)
    ).

```