new i delete a klasa abstrakcyjna

struct wirtualna
{
    virtual void costam() = 0;
};

class a
    : public wirtualna
{
    virtual void costam() override;
};

class b
    : public wirtualna
{
    virtual void costam() override;
};

int main()
{
   
    wirtualna * wskaznik = new a;
   
    wskaznik->costam();
   
    delete wskaznik;
   
}