class Super { 
  void who() { 
    System.out.println("volani v Super"); 
  } 
} 
 
class Sub1 extends Super { 
  void who() { 
    System.out.println("volani v Sub1"); 
  } 
} 
 
class Sub2 extends Super { 
  void who() { 
    System.out.println("volani v Sub2"); 
  } 
} 
 
class Dynam { 
  public static void main(String args[]) { 
    Super superOb = new Super(); 
    Sub1 subOb1 = new Sub1(); 
    Sub2 subOb2 = new Sub2(); 
 
    Super supRef;  
 
    supRef = superOb;  
    supRef.who(); 
 
    supRef = subOb1;  
    supRef.who(); 
 
    supRef = subOb2;  
    supRef.who(); 
  } 
}