下面程序的输出结果为：Base:: fun，请将程序补充完整。
include ＜iostream.h＞
class Base{
public:
【 】 fun(){cout＜＜"Base::fun"＜＜end1:}
class Derived : public Base{
public:
【 】 fun(){ cout＜＜"Derived::fun"＜＜end1; }
};
int main()
{
Base a,*pb;
Derived b;
pb = &b;
pb-＞fun();
return 0;
}