public static class DoubleNode {
            public int value;
            public DoubleNode last;
            public DobleNode next;

            public DoubleNode(int data) {
                this.val = data;
            }
        }

public static DoubleNode reverseDoubleList(DoubleNode head){ 
       DoubleNode pre=null;
       DoubleNode next=null;
       while(head != null){
		 next=head.next;
		 head.next=pre;
		 head.last=next;
		 pre=head;
		 head=next;
	   }
       return pre;
}