Please help with Prolog Program

list_index(X,List,N) is satisfied if the Nth item of List is X. Test the goals, list_index(X,[a,b,c],4), list_index(c,[a,c,b],N), list_index(a,[b,c,d],N), list_index(X,[],N). Keep in mind that the index of the first item in a list is 1, not 0. So, list_index(a,[a,b],N) must return N = 1.