#include <iostream>
using namespace std;

int main()
{
    int a= 10;
    int &r = a;
    
    cout <<"a : "<<a<<"  r : "<<r<<endl;
    
    r= 25;
    cout <<"a : "<<a<<"  r : "<<r<<endl;
    
    int b=30;
    r=b;
    cout <<"b : "<<b<<"  a : "<<a<<"  r : "<<r<<endl;
    
  return 0;
}