#include<iostream.h>

int main()
{
int a=10;
int &b=a;

cout<<"B"<<'\n'<<b;
cout<<"A"<<'\n'<<a;
b=100;
cout<<"B"<<'\n'<<b;
cout<<"A"<<'\n'<<a;
int c=20;
b=c;

cout<<"C"<<'\n'<<c;
cout<<"B"<<'\n'<<b;
}