写出下面程序的执行结果：

#include<iostream>

using namespace std;

class AA{

int a;

public :

AA( ){cout<<"Initualizing  AA!
";}

~AA( ){cout<<"Destroying  AA!
";}

};

class BB{

int b;

AA p;

public :

BB( ){cout<<"Initualizing  BB!
";}

~BB( ){cout<<"Destroying  BB!
";}

};

int main( )

{

BB X;

    cout<<"Ending main!
";

    return 0;

}