341_prolog

:- set_prolog_flag(double_quotes, chars).

l_c_prefix([], []).
l_c_prefix([H], H).
l_c_prefix([H1,H2|T], P) :-
    maplist(append(P), L, [H1,H2|T]),
    (   empty_h(L)
    ;   maplist(head, L, Hs),
        not_equal(Hs)
    ).

empty_h([[]|_]).
empty_h([[_|_]|T]) :-
    empty_h(T).

head([H|_], H).

not_equal([E|Es]) :-
    differences(Es, E).

differences([X|Xs], E) :-
    if_(first_diff(X,E), true, differences(Xs,E)).

first_diff(X, Y, T) :-
    (   X == Y -> T = false
    ;   X \= Y -> T = true
    ;   T = true,  dif(X, Y)
    ;   T = false, X = Y
    ).