有以下程序:
#included<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;
该程序运行后的输出结果是______。