class ChainNode2{
   
   //intances
   
      int element;
      ChainNode2 next;
      ChainNode2 previous;
   
   //constructor
   
      public ChainNode2(int element, ChainNode2 next, ChainNode2 previous){
         this.element = element;
         this.next = next;
         this.previous = previous;
      }
   }