text: #include<iostream>
  
  using namespace std;
  
  class Base {
  public:
    virtual void f(){
      cout << "Base" << endl;
    }
  };
  
  class D1 : virtual public Base {
  public:
    void f(){
      cout << "D1" << endl;
    }
  };
  
  int main(){
    Base b;
    b.f();
  }
  
  