the memory of virtual base class of C++

class X ...{};




class Y : public virtual X ...{};




class Z : public virtual X ...{};




class A : public Y, public Z ...{};




class A2: public virtual Y, public virtual Z ...{};






int main()...{


cout<<sizeof(X)<<endl; // 1


cout<<sizeof(Y)<<endl; // 4


cout<<sizeof(A)<<endl; // 8


cout<<sizeof(A2)<<endl; // 12 ??


return 1;


}