#include<iostream>
using namespace std;
class Base
{
public:
    Base(){x=0;}
    int x;
};
class Derived1:virtual public Base
{
public:
    Derived1(){x=10;}
};
class Derived2:virtual public Base
{
public:
    Derived2(){x=20;}
};
class Derived:public Derived1,protected Derived2
{};
int main()
{
    Derived obj;
    cout<<obj.x<<endl;
    return 0;
}
输出结果是20，我想知道原因，请大大们给我解释。