有以下程序
#include ＜iostream＞
using namespace std;
class Base

int a;
public:
Base(int x) a=x;
void show() cout＜＜a;
class Derived : public Base

int b;
public:
Derived(int i) :Base(i+1),b(i)
void show() cout＜＜b;
;
int main ()

Base b(5),*pb;
Derived d(1);
pb=&d;
pb-＞show ();
return 0;

运行后的打印结果是______。

AC’97规范