class Car {
    String licenceNum;
    int doors;
    Person owner;

    Car(String licenceNum_, int doors_, Person owner_) {
        licenceNum = licenceNum_;
        doors = doors_;
        owner = owner_;
    }

    boolean isValid() {
        return !licenceNum.isEmpty()
            && (doors == 3 || doors == 5)
            && owner != null
            && owner.isAdult(2016);
    }

    public String toString() {
        return licenceNum + " " + doors + " doors, owner: " + owner; // owner.toString();
    }
}