program of nesting class

#include<iostream.h>
#include<conio.h>
class A
{
public:
int a;
class B
{
public:
int b;
void show()
{
cout<<"2nd class\n";
cout<<"enter value of b \n";
cin>>b;
}
};
B bj;
void put()
{
cout<<"1st class\n";
cout<<"enter value of a \n";
void show();
}
}aj;
void main()
{
clrscr();
aj.put();
bj.show();
getch();
}