填空题

下列程序的运行结果是______。
#include＜iostream.h＞
class Base
public:
void f(int x)cout＜＜"Base:"＜＜x＜＜endl;
;
class Derived:public Base
public:
void f(char*str)cout＜＜"Derived:"＜＜str＜＜endl;)
;
void main(void)
Base*pd=new Base;
pd=new Derived;
pd-＞f(’a’);