填空题

下列程序的输出结果为2，请将程序补充完整。
#include ＜iostream＞
using namespace std;
class Base
public:
______void fun() cout＜＜1;
;
class Derived:public Base
public:
void fun()cout＜＜2;
;
int main()
Base*p=new Derived;
p-＞fun();
delete p;
return 0;