填空题

有如下程序:
#include <iostream>
using namespaee std;
class ONE
public:
virtual void f( )cout<<"1";

class TWO:public ONE
public:
TWO( )1 cout<<"2";

class THREE:public TWO
public:
virtual void f( )TWO::f( );cout<<"3";

int main( )
ONE aa,*P;
TWO bb;
THREE cc;
P=&cc;
p->f( );
return 0;
程序的输出结果是______。

【参考答案】

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