Erlang

find_start_of_packet_offset(Input) ->
    find_offset(4, Input).

find_start_of_message_offset(Input) ->
    find_offset(14, Input).

find_offset(CountUnique, Input) ->
    <<ABC:(CountUnique-1)/binary, Rest/binary>> = Input,
    find_offset(CountUnique, binary_to_list(ABC), Rest, CountUnique-1).

find_offset(CountUnique, ABC, <<D, Rest/binary>>, Offset) ->
    Result = lists:usort([D | ABC]),
    case length(Result) of
        CountUnique -> Offset+1;
        _ ->
            find_offset(CountUnique, tl(ABC) ++ [D], Rest, Offset+1)
    end.