填空题

下列程序的输出结果是______。
#include ＜iostream＞
using namespace std;
class base
public:
int n;
base(int x)n=x;
virtualvoid set(int m)n=m;cout＜＜n＜＜’ ’;
;
class deriveA:public base
public:
deriveA(int x):base(x)
void set(int m) n+=m,cout＜＜n＜＜’ ’;
;
class deriveB:public base
public:
deriveB(int x):base(x)
void set(int m) n+=m; cout＜＜n＜＜’ ’;
;
int main()

deriveA.d1(1);
deriveB.d2(3);
base *pbase;
pbase=&d1;
pbase-＞set(1);
pbase=&d2;
pbase-＞set(2);
return 0;

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